Ask Captain Lim - Can you speed up the Boeing 777 by flooring the throttles at 35,000 feet?

Thanks for the reply to my earlier question. The PWs have 8,000 lbs. more thrust than the RR so do you think the acceleration would be markedly different? Can you make the airplane go faster at cruise altitude? What would happen if you floored the throttle at 35,000 feet in level flight, would the airplane speed up rapidly?! I imagine this is horribly fuel inefficient and no airline pilot would do this but I just wonder. Did you see the 777-300ER has had her first flight last week? There is a link where people can get a video clip.

http://www.boeing.com/news/releases/2003/q1/nr_030224g.html

I have a further question. I am contemplating taking flying lessons, however I have a bust eardrum in my right ear. It doesn't cause me any discomfort flying on ordinary pressurized airplanes like the 777 but do you think it could be a problem in something like a Cessna? I was advised against skydiving because of this.

I would appreciate your advice as a first port of call, I would of course consult a doctor and I imagine I will need a medical anyway. I can actually hear a conversation from 6' easily but there is no way any airline would consider me precisely because of this reason, and I am happy doing what I am doing I just would like to fly as a hobby in the future.

Thanks for your help.

Howard

Hi Howard,

When you made comparison of engine thrusts of different airplanes, you have to be specific as to the Model number. For example, the RR Trent 892 engines produce a maximum thrust of 90,300 lbs each whereas the RR Trent 884 has only a 86,400 lbs thrust rating. Both are fitted on the Boeing 777's. So which PWs engines are you referring to?

Sure, you can make the plane fly faster during cruise but it would be uneconomical! The power setting of the Boeing 777 is controlled by a computer (EEC). If the EEC is working, you can floor the throttles (this is not like a car accelerator!) or in reality, the thrust levers are pushed to full forward, the speed would still be controlled by the auto throttles to whatever is being set or programmed. However, if the auto throttles are overridden, the speed can exceed the designed speed. A warning will come on to remind the pilots that the maximum speed is exceeded. At 35,000 feet, the Boeing 777 cruises at Mach 0.84 or 84 % the speed of sound. The maximum speed would be in the region of around Mach 0.86 or the red mark in the speed indicator. So there isn't much speed to go further and it would not really speed up any much faster than you would have imagined! I did not see the launching of the Boeing 777-300ER as I was busy flying around somewhere.

If you have a burst ear drum, it may affect your medical examination if you wish to pursue a career in Airline flying. It didn't cause you much discomfort when you flew as a passenger because the Boeing 777 is pressurized and the cabin altitude is less than that of an unpressurized Cessna. However, it should not affect you very much if you decide to fly as a hobby because, I believe the medicals for a Private Pilot's License is less stringent.

I have two pilot friends who had ruptured eardrum but after treatment, they are now flying again. Both are Captains. One flies the Boeing 747 and the other, a Boeing 737.