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A military aircraft, flying at FL270 near the top of a thunderstorm, encounters an updraft and comes within 500 ft in altitude of an opposite direction airliner at FL280.
| Attributes | |
| ACN | 403876 |
| Time | |
| Date | 199805 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : dfw |
| State Reference | TX |
| Altitude | msl bound lower : 27000 msl bound upper : 27500 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zfw |
| Operator | other |
| Make Model Name | Military Transport |
| Operating Under FAR Part | other : unknown |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : military |
| Function | flight crew : first officer |
| Qualification | pilot : military pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 2200 flight time type : 450 |
| ASRS Report | 403876 |
| Person 2 | |
| Affiliation | government : military |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : military |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : nmac inflight encounter : weather non adherence : clearance other anomaly |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : exited adverse environment flight crew : regained aircraft control flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Miss Distance | horizontal : 100 vertical : 500 |
| Supplementary | |
| Primary Problem | Weather |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
Transiting from nfw to nqx we had temporarily leveled off at FL270 in order to work around twring cumulo nimbus. An airline jet was on the same track, opposite direction, at FL280. At FL270, our flight path took us over a twring cumulo nimbus. I felt that skimming the top of the cloud was acceptable. However, the updraft of the clear air above the thunderstorm was strong enough to push the aircraft up 500 ft above FL270. Autoplt was on but not able to counter the updraft. Both pilots ended up pushing full forward on the yoke without effecting a rate of descent. Autoplt was turned off after a few seconds, at about the same time we flew out of the updraft. TCASII RA had actuated due to the jet at FL280. The other aircraft noted our altitude excursion when he checked off frequency, however, center did not mention it to us. Although I have been thoroughly trained to respect thunderstorms, I had no experience with lifting in clear air above cumulo nimbus. That is my lesson learned.
Original NASA ASRS Text
Title: A MIL ACFT, FLYING AT FL270 NEAR THE TOP OF A TSTM, ENCOUNTERS AN UPDRAFT AND COMES WITHIN 500 FT IN ALT OF AN OPPOSITE DIRECTION AIRLINER AT FL280.
Narrative: TRANSITING FROM NFW TO NQX WE HAD TEMPORARILY LEVELED OFF AT FL270 IN ORDER TO WORK AROUND TWRING CUMULO NIMBUS. AN AIRLINE JET WAS ON THE SAME TRACK, OPPOSITE DIRECTION, AT FL280. AT FL270, OUR FLT PATH TOOK US OVER A TWRING CUMULO NIMBUS. I FELT THAT SKIMMING THE TOP OF THE CLOUD WAS ACCEPTABLE. HOWEVER, THE UPDRAFT OF THE CLR AIR ABOVE THE TSTM WAS STRONG ENOUGH TO PUSH THE ACFT UP 500 FT ABOVE FL270. AUTOPLT WAS ON BUT NOT ABLE TO COUNTER THE UPDRAFT. BOTH PLTS ENDED UP PUSHING FULL FORWARD ON THE YOKE WITHOUT EFFECTING A RATE OF DSCNT. AUTOPLT WAS TURNED OFF AFTER A FEW SECONDS, AT ABOUT THE SAME TIME WE FLEW OUT OF THE UPDRAFT. TCASII RA HAD ACTUATED DUE TO THE JET AT FL280. THE OTHER ACFT NOTED OUR ALT EXCURSION WHEN HE CHKED OFF FREQ, HOWEVER, CTR DID NOT MENTION IT TO US. ALTHOUGH I HAVE BEEN THOROUGHLY TRAINED TO RESPECT TSTMS, I HAD NO EXPERIENCE WITH LIFTING IN CLR AIR ABOVE CUMULO NIMBUS. THAT IS MY LESSON LEARNED.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.