|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||atc facility : pub|
|Altitude||msl bound lower : 35000|
msl bound upper : 35500
|Controlling Facilities||artcc : zdv|
|Operator||common carrier : air carrier|
|Make Model Name||Medium Large Transport, Low Wing, 2 Turbojet Eng|
|Navigation In Use||Other |
|Flight Phase||cruise other|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Qualification||pilot : flight engineer|
pilot : atp
|Experience||flight time last 90 days : 180|
flight time total : 20000
flight time type : 3000
|Affiliation||company : air carrier|
|Function||flight crew : first officer|
|Qualification||pilot : atp|
|Anomaly||altitude deviation : excursion from assigned altitude|
inflight encounter other
non adherence : clearance
|Independent Detector||other flight crewa|
|Resolutory Action||flight crew : exited adverse environment|
|Air Traffic Incident||other|
En route cruise msp to phx, FL350, clear. Reported some mountain wave activity earlier in day. Gross weight 112000 pounds. Smooth ride for approximately 45 mins then encountered light mountain wave, no problem. Suddenly encountered moderate to severe mountain wave. Passenger previously strapped in. Unable to maintain airspeed within limits despite gross throttle corrections. Had to climb 500 ft twice due to excess speed, notified ATC! Got block altitude FL350-FL360 and requested earliest descent. Descent accomplished. Ride improved rapidly as mountain wave diminished. This is the second time going to altitude below the 1.5 G margin has bitten me. Our charts indicate 105000 pounds for 1.5 G and 130000 pounds for 1.25 G protection at FL350. This aircraft's wing does not belong up at altitude at the 1.25 G limit weight. The margin (high/low) is too small. It is unsafe! Many pilots do it trying to save fuel. Mistake! The FAA and the company need to correct this situation. Note: the medium large transport automatic throttles are useless in turbulence. You must immediately go to manual throttles as the aircraft always wants to overspd.
Original NASA ASRS Text
Title: ACR PIC COMPLAINS OF HIS MLG ACFT PERFORMANCE CAPABILITIES AT CERTAIN WTS WITH REF TO HIGHER ALTS AND ALLOWABLE G FORCE CTL LIMITS. ALTDEV ALT EXCURSIONS TO CTL AIRSPD DEVS IN MOUNTAIN WAVE.
Narrative: ENRTE CRUISE MSP TO PHX, FL350, CLR. RPTED SOME MOUNTAIN WAVE ACTIVITY EARLIER IN DAY. GROSS WT 112000 LBS. SMOOTH RIDE FOR APPROX 45 MINS THEN ENCOUNTERED LIGHT MOUNTAIN WAVE, NO PROB. SUDDENLY ENCOUNTERED MODERATE TO SEVERE MOUNTAIN WAVE. PAX PREVIOUSLY STRAPPED IN. UNABLE TO MAINTAIN AIRSPD WITHIN LIMITS DESPITE GROSS THROTTLE CORRECTIONS. HAD TO CLB 500 FT TWICE DUE TO EXCESS SPD, NOTIFIED ATC! GOT BLOCK ALT FL350-FL360 AND REQUESTED EARLIEST DSCNT. DSCNT ACCOMPLISHED. RIDE IMPROVED RAPIDLY AS MOUNTAIN WAVE DIMINISHED. THIS IS THE SECOND TIME GOING TO ALT BELOW THE 1.5 G MARGIN HAS BITTEN ME. OUR CHARTS INDICATE 105000 LBS FOR 1.5 G AND 130000 LBS FOR 1.25 G PROTECTION AT FL350. THIS ACFT'S WING DOES NOT BELONG UP AT ALT AT THE 1.25 G LIMIT WT. THE MARGIN (HIGH/LOW) IS TOO SMALL. IT IS UNSAFE! MANY PLTS DO IT TRYING TO SAVE FUEL. MISTAKE! THE FAA AND THE COMPANY NEED TO CORRECT THIS SIT. NOTE: THE MLG AUTO THROTTLES ARE USELESS IN TURB. YOU MUST IMMEDIATELY GO TO MANUAL THROTTLES AS THE ACFT ALWAYS WANTS TO OVERSPD.
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.