Ask Captain Lim - Could the Boeing 777 fall apart if you had a very strong tail wind?

You have a very interesting site there, congratulations!

I have just flown back to Gatwick, U.K from Bridgetown, Barbados. We did the journey in 7hrs 20 mins! (on a Boeing 777). The Captain said that we could have done it quicker as we had a tail wind of 100 mph most of the journey, but he couldn't land until 0602 at Gatwick, the first landing of the day I think.

I was watching the seat screen at various times during the flight and noticed that at one point we where doing 688 mph!! What is the maximum speed this plane could fly at? If we had a stronger tail wind for example, could we have broken 700/750mph? I suppose at some point the aircraft would start to fall apart!?

I was also going to ask if I could visit the flight deck on this flight. I was pleased I didn't because I was unaware that this practice was stopped after Sep11th... maybe one day though..

Many thanks in advance, Kind regards,

Dan Parker

Hi Dan,

You are asking an almost similar question that was raised twice before. What you saw was the GROUND speed of 688 mph. The airplane was flying at a constant TRUE AIR speed of 588 mph. You had a tail wind of 100 mph and any strong tailwind is a bonus to the pilot! It saves time and fuel. He gets to go home early too!

A layman find it difficult to understand this. When an airplane is flying, it is in fact floating in a parcel of air. You can get a tail wind as strong as 250 mph, especially in the core of a jet stream. When the airplane cruising at a true air speed of 588 mph in that parcel of air is blown by an external force, for instance, a very strong tail wind of 250 mph, your total speed or what we call the GROUND speed is now 838 mph! As far as the airplane is concerned, it is still cruising at 588 mph and would not exceed it maximum designed speed. It would not fall apart!

When you drive a car, you only refer to one speed on the road. When you fly, you have two types of speed and most people are interested in the GROUND speed rather than the TRUE AIR speed. A pilot will avoid a strong head wind by flying away from a jet stream because the opposite effect will take place!

I hope I have been able to explain the effect of tail wind on the Boeing 777.

Happy flying... always with a tail wind!