American Airlines 1420
Accident Case Study
The crew on this MD-82 was highly qualified and accomplished. The captain was an Air Force veteran and a highly experienced check airman with American Airlines. His record was enviable. The first officer was new to American Airlines but was a Navy veteran with a good record. And yet they made a series of foolish mistakes that I am sure neither would have made the day before or the day after. What happened?
The NTSB report cited the crew's failure to abandon the approach and failure to arm the automatic ground spoilers. The crosswinds were above their company's stated maximum for a wet runway. At one point the captain said, "I hate droning around visual at night in weather without, having some clue where I am." No doubt about it, the approach should have been abandoned. Why did they start the approach, why did they continue the approach, and why didn't they go around and divert?
Experienced pilots know the reason: get-there-itis. We all have a mission-oriented instinct to get to our destination. It is, after all, our job.
This airline crew had that schedule pressure and I am told it was ingrained in many American Airlines pilots at the time. I am also told that culture has changed.
Figure: N215AA, from "Pressing the Approach", pg. 28.
- Date: 01 JUN 1999
- Time: 23:51
- Type: McDonnell Douglas MD-82
- Operator: American Airlines
- Registration: N215AA
- Fatalities:1 of 6 crew, 11 of 145 passengers
- Aircraft Fate: Destroyed
- Phase: Landing
- Airports: (Departure) Dallas/Fort Worth International Airport, TX (DFW/KDFW), United States of America; (Destination) Little Rock National Airport, AR (LIT/KLIT), United States of America<
Figure: Flight 1420's Approach Path, from NTSB Report, Figure 1.
[NTSB Report, pg. 1]
- Flight 1420, from Dallas/Fort Worth to Little Rock, was scheduled to depart about 2028 and arrive about 2141. However, before its arrival at Dallas/Fort Worth, the flight crew received an aircraft communication addressing and reporting system (ACARS) message indicating a delayed departure time of 2100 for flight 1420. After deplaning from flight 2080, the flight crew proceeded to the departure gate for flight 1420. The flight crew then received trip paperwork for the flight, which included an American Airlines weather advisory for a widely scattered area of thunderstorms along he planned route and two National Weather Service (NWS) in-flight weather advisories for an area of severe thunderstorms4 along the planned route.
- The airplane originally intended to be used for the flight was delayed in its arrival to Dallas/Fort Worth because of the adverse weather in the area. After 2100, the first officer notified gate agents that flight 1420 would need to depart by 2316 because of American’s company duty time limitation. The first officer then telephoned the flight dispatcher to suggest that he get another airplane for the flight or cancel it. Afterward, the accident airplane, N215AA, was substituted for flight 1420. The flight’s 2240 departure time was 2 hours 12 minutes later than the scheduled departure time. The captain was the flying pilot, and the first officer was the nonflying pilot.
- About 2254, the flight dispatcher sent the flight crew an ACARS message indicating that the weather around Little Rock might be a factor during the arrival. The dispatcher suggested that the flight crew expedite the arrival to beat the thunderstorms if possible, and the flight crew acknowledged this message. The first officer indicated, in a postaccident interview, that “there was no discussion of delaying or diverting the landing” because of the weather. According to the predeparture trip paperwork, two alternate airports—Nashville International Airport, Tennessee, and Dallas/Fort Worth— were specified as options in case a diversion was needed.
- Beginning about 2258, flight 1420 was handled by controllers from the Fort Worth Air Route Traffic Control Center (ARTCC). About 2304, the Fort Worth center broadcast NWS Convective SIGMET [significant meteorological information] weather advisory 15C for an area of severe thunderstorms that included the Little Rock airport area. The cockpit voice recorder (CVR) indicated that the flight crew had discussed the weather and the need to expedite the approach. At 2325:47, the captain stated, “we got to get over there quick.” About 5 seconds later, the first officer said, “I don’t like that...that’s lightning,” to which the captain replied, “sure is.” The CVR also indicated that the flight crew had the city of Little Rock and the airport area in sight by at 2326:59.
- About 2327, the Fort Worth center cleared the flight to descend to 10,000 feet mean sea level (msl) and provided an altimeter setting of 29.86 inches of mercury (Hg). The flight was transferred about 2328 to the Memphis ARTCC, which provided the same altimeter setting.
- According to the CVR, the flight crew contacted the Little Rock Air Traffic Control Tower (ATCT) at 2334:05. The controller advised the flight crew that a thunderstorm located northwest of the airport was moving through the area and that the wind was 280o at 28 knots gusting to 44 knots. The first officer told the controller that he and the captain could see the lightning. The controller told the flight crew to expect an ILS approach to runway 22L. The first officer indicated in a postaccident interview that, during the descent into the terminal area, the weather appeared to be about 15 miles away from the airport and that he and the captain thought that there was “some time” to make the approach.
- The CVR indicated that, between at 2336:04 and at 2336:13, the captain and first officer discussed American Airlines’ crosswind limitation for landing. The captain indicated that 30 knots was the crosswind limitation but realized that he had provided the limitation for a dry runway. The captain then stated that the wet runway crosswind limitation was 20 knots, but the first officer stated that the limitation was 25 knots. In testimony at the National Transportation Safety Board’s public hearing on this accident, the first officer stated that neither he nor the captain checked the actual crosswind limitation in American’s flight manual. The first officer testified that he had taken the manual out but that the captain had signaled him to put the manual away because the captain was confident that the crosswind limitation was 20 knots.
- At 2339:00, the controller cleared the flight to descend to an altitude of 3,000 feet msl. The controller then asked the flight crew about the weather conditions along the runway 22L final approach course, stating his belief that the airplane’s weather radar was “a lot better” than the weather radar depiction available in the tower. At 2339:12, the first officer stated, “okay, we can...see the airport from here. We can barely make it out but we should be able to make [runway] two two...that storm is moving this way like your radar says it is but a little bit farther off than you thought.” The controller then offered flight 1420 a visual approach to the runway, but the first officer indicated, “at this point, we really can’t make it out. We’re gonna have to stay with you as long as possible.”
- At 2339:45, the controller notified flight 1420 of a windshear alert, reporting that the centerfield wind was 340° at 10 knots, the north boundary wind was 330° at 25 knots, and the northwest boundary wind was 010° at 15 knots. The flight crew then requested runway 4R so that there would be a headwind, rather than a tailwind, during landing. At 2340:20, the controller instructed the flight crew to fly a heading of 250° for vectors to the runway 4R ILS final approach course. After reaching the assigned heading, the airplane was turned away from the airport and clear of the thunderstorm that had previously been reported by the controller. The CVR indicated that, between 2340:46 and 2341:31, the first officer stated the localizer frequency and course, the decision altitude, the minimum safe altitude, and a portion of the missed approach procedure for runway 4R.
- Between 2342:19 and 2342:24, the CVR indicated that the captain asked the first officer, “do you have the airport? Is that it right there? I don’t see a runway.” At 2342:27, the controller told the flight crew that the second part of the thunderstorm was apparently moving through the area and that the winds were 340° at 16 knots gusting to 34 knots. At 2342:40, the first officer asked the captain whether he wanted to accept “a short approach” and “keep it in tight.” The captain answered, “yeah, if you see the runway. ‘cause I don’t quite see it.” The first officer stated, “yeah, it’s right here, see it?” The captain replied, “you just point me in the right direction and I’ll start slowing down here.” At 2342:55, the first officer said, “it’s going right over the...field.” At 2342:59, the first officer told the controller, “well we got the airport. We’re going between clouds. I think it’s right off my, uh, three o’clock low, about four miles.” The controller then offered a visual approach for runway 4R, and the first officer accepted. At 2343:11, the controller cleared flight 1420 for a visual approach to runway 4R and indicated “if you lose it, need some help, let me know please.”
- At 2343:35, the first officer stated, “you’re comin’ in. There’s the airport.” Three seconds later, the captain stated, “uh, I lost it,” to which the first officer replied, “see it’s right there.” The captain then stated, “I still don’t see it...just vector me. I don’t know.” At 2343:59, the controller cleared flight 1420 to land and indicated that the winds were 330° at 21 knots. At 2344:19, the captain stated, “see we’re losing it. I don’t think we can maintain visual.” At 2344:30, the first officer informed the controller that visual contact with the airport had been lost because of a cloud between the airplane and the airport. The controller then cleared the airplane to fly a heading of 220° for radar vectors for the ILS approach to runway 4R and directed the flight to descend to and maintain 2,300 feet msl.
The captain was correct.
[NTSB Report, pg. 204 (CVR)]
- 1145:15 CAM-1: I hate droning around visual at night in weather without, having some clue where I am.
- 1145:23 CAM-2: Yeah but, the longer we go out her . . .
- 1145:24 CAM-1: Yeah, I know.
The captain was obviously uncomfortable but appeared unwilling to call "knock it off" with the first officer being so willing to press on.
[NTSB Report, pg. 4]
- At 2345:47, the first officer told the controller “we’re getting pretty close to this storm. we’ll keep it tight if we have to.” The controller indicated to the flight crew that, “when you join the final, you’re going to be right at just a little bit outside the marker if that’s gonna be okay for ya.” The captain stated, “that’s great,” and the first officer told the controller, “that’s great with us.” At 2346:39, the controller advised the flight crew that the airplane was 3 miles from the outer marker.
- At 2346:52, the captain stated, “aw, we’re goin’ right into this.” At the same time, the controller reported that there was heavy rain at the airport, the automatic terminal information service (ATIS) information in effect at the time was no longer current, the visibility was less than 1 mile, and the runway visual range (RVR)15 for runway 4R was 3,000 feet. The first officer acknowledged this information. At 2347:08, the controller again cleared flight 1420 to land and indicated that the wind was 350° at 30 knots gusting to 45 knots. The first officer then read back the wind information as 030° at 45 knots. At 2347:22, the captain stated, “three thousand RVR. We can’t land on that.” Four seconds later, the first officer indicated that the RVR for runway 4R was 2,400 feet, and the captain then said, “okay, fine.”
- At 2347:44, the captain stated, “landing gear down,” and the CVR recorded a sound consistent with the landing gear being operated. About 5 seconds later, the captain stated, “and lights please.” At 2347:53, the controller issued a second windshear alert for the airport, reporting that the centerfield wind was 350° at 32 knots gusting to 45 knots, the north boundary wind was 310° at 29 knots, and the northeast boundary wind was 320° at 32 knots. This transmission was not acknowledged by the flight crew. At 2348:10, the captain stated, “add twenty [knots],” to which the first officer replied, “right.”
- At 2348:12, the controller reported that the runway 4R RVR was now 1,600 feet. About 2348:18, the captain indicated that the flight was established on final approach; 6 seconds later, the first officer informed the controller that the flight was established on the inbound portion of the ILS. The controller repeated the clearance to land; stated that the wind was 340° at 31 knots, the north boundary wind was 300° at 26 knots, and the northeast boundary wind was 320o at 25 knots; and repeated the RVR. At 2348:41, the first officer acknowledged this information. The controller did not receive any further transmissions from flight 1420. At 2349:02, the first officer asked the captain, “want forty flaps?” The captain indicated that he thought he had already called for the landing flaps, after which the first officer stated, “forty now.” At 2349:10, the controller informed the flight crew that the wind was 330° at 28 knots. Two seconds later, the captain stated, “this is a can of worms.”
- According to the CVR, the first officer stated, “there’s the runway off to your right, got it?” at 2349:24. The captain replied, “no,” to which the first officer stated, “I got the runway in sight. You’re right on course. Stay where you’re at.” The captain then stated, “I got it. I got it.” At 2349:32, the controller reported the wind to be 330° at 25 knots. At 2349:37, an unidentified voice in the cockpit stated, “wipers,” and the CVR then recorded a sound consistent with windshield wiper motion. (This sound continued throughout the rest of the flight.) At 2349:53, the controller reported the wind to be 320° at 23 knots.
- The CVR indicated that, at 2349:57, an unidentified voice in the cockpit stated, “aw...we’re off course” and that, 1 second later, an unintelligible comment was made by an unidentified voice in the cockpit. In a postaccident interview, the first officer stated that he thought the approach was stabilized until about 400 feet above field level (afl), at which point the airplane drifted to the right. The first officer also stated that he said “go around” about that time but not in a very strong voice. The first officer indicated that he had looked at the captain to see if he had heard him but that the captain was intent on flying and was doing “a good job.”
- The CVR indicated that, at 2350:00, the first officer said, “we’re way off.” Flight data recorder (FDR) information indicated that the localizer deviation value was about one dot to the right at that point. About 1 second later, the captain stated, “I can’t see it.” About 3 seconds afterward, the first officer asked, “got it?” to which the captain replied, “yeah I got it.” At 2350:13 and :14, the CVR recorded the sound of the ground proximity warning system (GPWS) radio altitude callout “sink rate.” Calculations based on FDR data indicated that the airplane was descending through an altitude of about 70 feet afl at the time of the first sink rate warning and about 50 feet afl at the time of the second warning. Figure 1 shows flight 1420’s flightpath to Little Rock and runway 4R along with key CVR comments and the airplane’s location when the comments were made.
- FDR and CVR data indicated that the airplane touched down on the runway about 2350:20. About 2350:22, the first officer stated “we’re down;” about 2 seconds later, he stated, “we’re sliding.” FDR data also indicated that, over a 7-second period after touchdown, both thrust reversers were deployed and the left and right engines’ engine pressure ratios (EPR) reached settings of 1.89 and 1.67, respectively. The thrust reversers were subsequently moved to the unlocked status (neither deployed nor stowed). According to the FDR, the flight spoilers did not deploy symmetrically at touchdown, but a momentary 8° deflection of the left outboard flight spoiler concurrent with a left aileron deflection was recorded.
- FDR data indicated that the right and left brake pedals began to move at 2350:25 and :30, respectively, and both pedals reached full travel at 2350:31. About the time that the brakes were applied, the thrust reversers were deployed again. At 2350:32, the CVR recorded an unidentified voice in the cockpit stating “on the brakes.” The left engine reached a maximum setting of 1.98 reverse EPR, and the right engine reached a setting of 1.64 reverse EPR. The left brake pedal was relaxed at 2350:34 before returning to its full position 2 seconds later. About the time that the left brake pedal was relaxed, the reversers were returned to the unlocked status. As the right thrust reverser was being moved to the unlocked status, the right engine reached a maximum setting of 1.74 reverse EPR.
- At 2350:36, FDR data indicated a full 60° deployment of the right inboard flight spoiler, concurrent with a full aileron deflection. At 2350:40, the left thrust reverser was moved back to the deployed position, but the right reverser moved briefly to the deployed position and then moved to the stowed position. According to FDR data, the left thrust reverser remained deployed, and the right thrust reverser remained stowed, for the remainder of the flight. About 1 second later, the CVR recorded expletives stated by an unidentified voice in the cockpit, which were followed by the sounds of initial impact at 2350:44 and several additional impacts beginning at 2350:47. The CVR stopped recording at 2350:48. The airplane came to rest about 800 feet from the departure end of runway 4R, 34° 44.18 minutes north latitude and 92° 11.97 minutes west longitude. The accident occurred during the hours of darkness.
That statement should have intuitively told both pilots it was time to go around.
The "off course" should have been a cue to go around. The actual go around call should have been made more assertively and when not executed, should have been repeated.
[NTSB Report, ¶184.108.40.206] 220.127.116.11 Use of Reverse Thrust
- American Airlines’ DC-9 Operating Manual, Volume 1, Techniques, page 21, (dated November 15, 1995), indicates the following:
- The application of reverse thrust tends to blank out the rudder. The effectiveness of the rudder starts decreasing with the application of reverse thrust and at 90 knots, at 1.6 EPR (in reverse) it is almost completely ineffective.
- If the airplane starts drifting across the runway while reversing, immediately return the reverse thrust levers to idle reverse to assist in regaining directional control and to restore rudder effectiveness.
- American’s DC-9 Operating Manual, Volume 1, Environmental, page 7 (dated April 26, 1999), states the following under the heading “Slippery Runway – Crosswind”:
- One of the worst situations occurs when there is a crosswind and sufficient water and speed to produce total tire hydroplaning. Reverse thrust tends to disrupt airflow across the rudder and increase the tendency of the airplane to drift downwind, especially if a crab or yaw is present.
- As reverse thrust increases above 1.3 EPR, rudder effectiveness decreases until it provides no control at about 1.6 EPR. Do not exceed 1.3 EPR reverse thrust on the slippery portions of the runway, except in an emergency.
- Page 27 includes the following guidance for landing on a slippery runway:
- Apply reverse thrust as soon as possible after nosewheel touchdown. Do not exceed 1.3 EPR reverse thrust on the slippery portions of the runway, except in an emergency.
- When reversing, be alert for yaw from asymmetric thrust. If directional control is lost, bring engines out of reverse until control is regained.
- Do not come out of reverse at a high RPM. Sudden transition of reversers before engines spool down will cause a forward acceleration.
[NTSB Report, ¶18.104.22.168] National Aeronautics and Space Administration Study on Flight Crew Decision Errors
- The NASA researchers found that the most common decision errors occurred when the flight crew decided to “continue with the original plan of action in the face of cues that suggested changing the course of action.” The study stated that cues that signal a problem are not always clear and that a decision-maker’s situation assessment may not keep pace with conditions that deteriorate gradually. The study also stated that individuals have a natural tendency to maintain their originally selected course of action until there is clear and overwhelming evidence that the course of action should be changed. Further, the study stated the following:
- [A] recurring problem is that pilots are not likely to question their interpretation of a situation even if it is in error. Ambiguous cues may permit multiple interpretations. If this ambiguity is not recognized, the crew may be confident that they have correctly interpreted the problem. Even if the ambiguity is recognized, a substantial weight of evidence may be needed to change the plan being executed.
- In addition, the study noted that pilots under stress might not evaluate the consequences of various options.
[NTSB Report, ¶22.214.171.124] Summary of the Flight Crew’s Performance During the Approach
- As the flight crew was maneuvering the airplane for landing, there were events that, individually, might not necessitate aborting an approach: a runway change because of a shifting wind, a failed visual approach to the newly assigned runway, the temporary inability of the airborne weather radar to show the weather conditions at the airport because of the airplane’s direction of travel, the controller’s report of the second part of the thunderstorm moving through the airport area, and the acceptance of a short approach near the outer marker because of the airplane’s location in relation to the storm. However, these events, collectively, should have heightened the crewmembers’ awareness that they might not be able to safely continue the approach. Thus, it would have been appropriate for the flight crew to have discussed specific options (holding, diverting to one of the two alternate airports, or performing a missed approach after the airplane was established on the final approach segment) in the event that the weather would necessitate aborting the approach later.
- During the final approach, the flight crew had a significant amount of weather information that had to be simultaneously evaluated. This information included the controller’s previous report of heavy rain at the airport with visibility less than 1 mile, the second windshear alert,190 a rapidly decreasing RVR, and several wind reports. Under these circumstances, some flight crews would have decided to abandon the approach.
- The flight 1420 crew then poorly performed, and did not complete, the second half of the Before Landing checklist. Although the sound of the landing gear being operated was recorded by the CVR, there is no CVR evidence to indicate that the first officer verbalized this checklist item as “down, three green” as required, which would have indicated that all three landing gear systems were in the down and locked position. Also, the captain commanded the 40° final landing flap configuration only after being queried by the first officer. As previously stated, the captain did not realize that he had not yet called for the flaps; as a result, this checklist item was performed late. In addition, there is no CVR evidence to indicate that the first officer called out that the spoiler lever was armed, checked the annunciator lights, and completed the Before Landing checklist or that either pilot had armed the spoiler lever and considered the use of automatic rather than manual braking in light of the deteriorating weather conditions.
- As previously discussed, the flight crew should have initiated a go-around during the final approach segment when a specific operational criterion was not met, that is, when the company’s maximum crosswind component for conducting the landing was exceeded. The flight crewmembers’ failure to establish the final landing flap configuration before reaching 1,000 feet afl and their failure to maintain a normal rate of descent, under different circumstances, might not necessitate a go-around. However, the Safety Board concludes that, because of the flight crew’s failure to adequately prepare for the approach and the rapidly deteriorating weather conditions, the likelihood of safely completing the approach was decreasing, and the need to take a different course of action was progressively increasing; as a result, the flight crew should have abandoned the approach. Factors that contributed to the flight crew’s performance during the accident flight are discussed in section 2.2.3.
- Finally, it is important to note that a microburst, with a peak wind gust of 76 knots and rainfall rates of 9 inches per hour, impacted the airport shortly after the flight 1420 accident and thus was not a factor. NWS radar data, however, detected that the microburst was over runway 4R at 2353:00. Thus, if flight 1420’s takeoff, en route flight, or approach to landing had been delayed by less than 2 minutes, the flight could have encountered the microburst on final approach. Microbursts can result in vertical and horizontal windshear that can be extremely hazardous to aircraft, especially at low altitudes, as demonstrated by the 1994 USAir flight 1016 accident in Charlotte, North Carolina, and the 1985 Delta Air Lines flight 191 accident in Dallas, Texas (see section 1.18.5). As a result, the Safety Board is concerned that the flight crew was operating in an environment that was conducive to microburst conditions.192 Section126.96.36.199.1 presents an industry-wide recommendation to develop operational strategies and guidance to promote better flight crew decision-making regarding the penetration of severe convective activity.
[NTSB Report, ¶188.8.131.52.] American’s DC-9 Operating Manual indicated that, for landings on slippery runways, pilots were not to exceed 1.3 EPR on the “slippery portions of the runway” except in an emergency situation. Likewise, Boeing’s MD-80 FCOM indicated that reverse thrust of no more than 1.3 EPR should be used on wet or contaminated runways, except in an emergency. However, FDR evidence indicated that reverse thrust exceeded 1.3 EPR several times during flight 1420’s landing sequence.199 Further, American’s and Boeing’s maximum reverse thrust setting for landings on dry runways was 1.6 EPR, and FDR data showed that even this setting was exceeded many times during the landing.
[NTSB Report, ¶184.108.40.206.] The Safety Board’s Airplane Performance Study indicated that the accident airplane could have stopped about 700 feet before the end of the runway if the spoilers had deployed, a constant symmetrical reverse thrust at 1.3 EPR had been maintained, and the flight 1420 manual braking profile had been applied. In contrast, with the spoilers not extended, the airplane could not have stopped within the remaining runway length even if maximum manual braking had been applied immediately after touchdown and symmetrical reverse thrust at 1.3 EPR had been maintained throughout the landing roll. Thus, the Safety Board concludes that the lack of spoiler deployment was the single most important factor in the flight crew’s inability to stop the accident airplane within the available runway length.
[NTSB Report, ¶3.2] The National Transportation Safety Board determines that the probable causes of this accident were the flight crew’s failure to discontinue the approach when severe thunderstorms and their associated hazards to flight operations had moved into the airport area and the crew’s failure to ensure that the spoilers had extended after touchdown.
Contributing to the accident were the flight crew’s (1) impaired performance resulting from fatigue and the situational stress associated with the intent to land under the circumstances, (2) continuation of the approach to a landing when the company’s maximum crosswind component was exceeded, and (3) use of reverse thrust greater than 1.3 engine pressure ratio after landing.
Flight Safety Foundation, "MD-82 Overruns Runway While Landing in Proximity of Severe Thunderstorms," Accident Prevention, Vol. 59 No. 2, February 2002
Flight Safety Foundation, "Pressing the Approach," December 2006
May Day: Racing the Storm, Cineflix, Episode 2, Season 1, 3 September 2003 (American Airlines 1420)
NTSB Aircraft Accident Report, AAR-01/02, Runway Overrun During Landing, American Airlines Flight 1420, McDonnell Douglas MD-82, N215AA, Little Rock, Arkansas, June 1, 1999