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?

I've definitely seen ground speeds of 750+ mph on 747 flights over the Sea of Japan.

1,268 kilometres/hour, which is 787 miles/hour on a SQ flight from SIN to SYD many years ago with a ~300km/hour tailwind. The speed was reported by both the inflight system and my GPS (with a 2km/hour difference between the two)

Yes, that's technically faster than the speed of sound, but as it's relative to the air around the plane we weren't actually above the sound limit (obviously!)

We landed in SYD well before curfew, were met by an ambulance to handle the medical emergency which was the reason for the speed, and then had to wait for close to an hour before immigration arrived and we could deplane.

I don't remember the tailwind involved but once I tried to ask a FA about it as I thought our ground speed was supersonic and I was curious. Somewhere between her and the pilot there was a communications problem and I never got a proper answer. (TPAC, eastbound.)

groudspeedrecords.com is always a fun site to browse. A United aircraft holds the record for the 752: http://www.groundspeedrecords.com/in...39&Itemid=1764

I've seen over 600 knots (690 mph). The guy I was flying with on my last trip said he's seen over 700 knots (805 mph) in the B777. Had 598 knots (687 mph) last week in the 737.

Ground speed can be supersonic but all that matters is the true airspeed (the speed of the aircraft relative to the airmass in which it is flying). True airspeed is usually in the 430kts to 480kts (495mph to 552mph) range.

At cruise altitude, though, we use mach number, not airspeed. The speed of sound (mach 1.0) varies with temperature. We'll usually fly in the M0.72-M0.85 range depending on conditions, economy flight plan vs. speed, and the airplane. The true airspeed that produces varies based on temperature.

As an air traffic controller I have seen plus 800 ground speeds. It gets real interesting when you have Citation 10's doing mach .95 with a 200 knot tail wind.

I was on a ORD-IAD flight a few years back. Don't recall the exact speed, but it was well north of 700 mph and significant enough that the pilot called attention to it, statng that it did not happen over land often. The normal 1hr 31 min flight was done in an hour.

And then there's the opposite problem.... nearly eight hours BOS-SFO with a 150kt headwind. Yuck.

Interesting topic, particularly this time of year when winter wind speeds can make a significant flight time difference + or -. However, as the topic and discussion are not limited to United aircraft performance, let's share this with others via the TravelBuzz forum. I'll move it there. Ocn Vw 1K, Moderator, United.

I saw 800mph (695 knots) once - pilot said 220mph tailwinds. Iirc, SFO-PIT in just over 3.5 hours.

I remember watching the screen on a UA flight from NRT-ORD and the area right around Alaska where it always gets a little rough it seems...could have sworn it was in the 850mph range. I was pretty excited about that for sure.

I was on a Convair 880 flight where the Captain mentioned our ground speed was well in excess of 700 mph. On a Denver to New York JFK flight, we arrived JFK 40 minutes early.

Back when Braniff used to operate the Air France/British Airways Concorde interchange flights on the IAD-DFW run, the captain took us right up to Mach .99 - whatever speed that is

I've experienced similar speeds, but not recently. I've assumed that the airlines have figured out that they can cut back the speed, save fuel, and still arrive on schedule.

I don't have the photo that I took of the inflight map but I was on a NW 742 NRT-LAX. Flight took a southwesterly course out of NRT to catch the tailwinds which resulted in a ground speed of close to 1,200 km/h. Overall course was very southerly with the flight going about an hours flying time north of Hawaii.

And sometimes unavoidable. Was in a similar situation on a NW DC-10 from HNL-NRT plodding along at what seemed to be a very leisurely pace. Connection time dwindled so much the NW ground team in NRT had to gather all the pax connecting to BKK in a van as there was only 1/2 hr connecting time left (and the plane parked remotely).