Figure: Microburst, from WX Brief.

Eddie Sez:

By the time of this mishap, wind shear was a well recognized problem and the professional aviator class was well versed in how to recognize and how to deal with it. There was a thunderstorm overhead the airport and the airplane penetrated a microburst. The horizontal windshear was calculated to be as high as 86 knots. US Air 1016 was calculated to have gone through a 61 knot windshear in 15 seconds.

Still, reading through the NTSB Accident Report, one has to wonder if the crew could have anticipated the problem earlier, as the report alleges. They were preceded by other airplanes including one that reported a "smooth ride." The last thing they heard from tower was "windshear alert northeast boundary wind one nine zero at one three." They were headed for Runway 18R. I doubt a 13 knot wind would have prompted me to go around.

Once they decided to go around, I would agree, they made a few mistakes: they didn't set enough power, they allowed their pitch to fall below target, and they made a turn when flying straight ahead would have been okay. Simulations proved that they could have survived had the go around been flown properly.

So what to make of this? We have better radar and windshear detection today, to be sure. This crew should not have attempted the approach given the proximity of the weather. They didn't know what ground witnesses reported: "a wall of water" on top the airport. They didn't know what the weather service had just reported: "thunderstorm overhead the airport." But given the position of the cells to the airport, they should not have started the approach. The go around decision was smart, but the go around execution was not.

What follows are quotes from the relevant regulatory documents, listed below, as well as my comments in blue.


Accident Report


Narrative

[NTSB AAR 95/03, ¶1.7]


Analysis

[NTSB AAR 95/03, ¶1.6.2]

[NTSB AAR 95/03, ¶1.7.3]

[NTSB AAR 95/03, ¶2.2.1] USAir flight 1016 encountered a microburst windshear while on a missed approach from runway 18R. The microburst was the result of convective activity that was centered near the east side of runway 18R and that had cloud tops measured to an altitude of 30,000 feet. The microburst was determined to be approximately 3.5 kilometers in diameter and was capable of producing a rainfall rate of about 10 inches per hour. The total wind change near the ground was determined to be about 75 knots (at approximately 300 feet the winds were 86 knots), with the strongest downward vertical winds below 300 feet agl calculated to be 10 to 20 fps. The outflow winds most likely exhibited asymmetry with stronger winds on the west side of the microburst.

[NTSB AAR 95/03, ¶2.3]


Probable Cause

[NTSB AAR 95/03, ¶3.2] The National Transportation Safety Board determines that the probable causes of the accident were: 1) the flightcrew’s decision to continue an approach into severe convective activity that was conducive to a microburst; 2) the flightcrew’s failure to recognize a windshear situation in a timely manner; 3) the flightcrew’s failure to establish and maintain the proper airplane attitude and thrust setting necessary to escape the windshear; and 4) the lack of real-time adverse weather and windshear hazard information dissemination from air traffic control, all of which led to an encounter with and failure to escape from a mircroburst-induced windshear that was produced by a rapidly developing thunderstorm located at the approach end of runway 18R.


See Also

Abnormal Procedures / Spatial Disorientation

Abnormal Procedures / Windshear


References

NTSB Aircraft Accident Report, AAR-95/03, Flight Into Terrain During Missed Approach, USAir Flight 1016, DC-9-31, N954VJ, Charlotte/Douglas International Airport, Charlotte, North Carolina, July 2, 1994

WX Brief: Better knowledge of down bursts can save you from dangerous flying experiences, Karsten Shein, Professional Pilot, July 2013