Air carrier PIC complains of his medium large transport aircraft performance capabilities at certain weights with reference to higher altitudes and allowable G force control limits. Altitude deviation altitude excursions to control airspeed deviations in mountain wave.

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Attributes
ACN	234697
Time
Date	199302
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : pub
State Reference	CO
Altitude	msl bound lower : 35000 msl bound upper : 35500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
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
ASRS Report	234697
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
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
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

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.