Originally Posted by
BeanTownBoy
On UA 1279 IAH to BOS on 12/16 (B739), with blustery weather in the Northeastern US the Flight Map indicated that our speed at one point hit 686 mph. I was hoping to break 700 mph, but I could feel the engines reduced when we were in the 680 range. After deplaning, I waited for the pilots to ask a question. I approached a person in pilot's uniform and he said that he did not fly the plane (I assume he was non-rev?), but that the day before he flew the route and had a tailwind of 168 mph. Rather than waiting for this flight's pilots (who seemed to be waiting for all passengers to get off), I moved on to catch my ride. I started thinking, what was the maximum speed observed by other FT'ers on a commercial (Non-Concorde/SST) flight?
Let's keep in mind that there is a difference between Airspeed and Groundspeed. Airspeed is the rate at which the air is passing over the aircraft. Groundspeed is the speed point-to-point relative to the ground, and is really the one that makes the difference between getting there quickly or slowly.
When flying into a headwind, the airspeed can be very high, but the groundspeed much lower. There is lots of air passing quickly over the wings, but the headwind offers resistence and reduces the speed at which you are going over the ground.
In a tailwind, the airspeed can be low but the groundspeed can be very very high.
Airspeed/groundspeed can be thought of like a fish swimming in a bowl. The fish may be going 2mph from one end of the bowl to the other..but if the bowl is on a train going 40mph, the fish has a 42mph groundspeed. Fast fish!!
There is even a strange phenomena that is sometimes seen with smaller aircraft where the airspeed reduces groundspeed to 0. If you are going 80mph into and 80mph headwind, the aircraft will still fly but remain still..like it's hovering. There is enough airspeed to keep the aircraft flying, but no groundspeed.
Anyhow, it did not happen to me but to my sister several years ago. She was eastbound, from PHX to YYZ and I was watching the flight on flightaware. Somewhere around ORD there was a 170mph tailwind and the Airbus's groundspeed was pushing 700. She said the flight was amazingly short for that distance. Of course, people going westbound had the opposite effect and had very very low groundspeeds, making their flight longer.