737 flying mach 1

flightaware.com/live/flight/DAL7 … K/tracklog

Looks like it did it for about 4 minutes from 10:19AM to 10:23 AM

Is this correct? Can it be done?

I wouldn’t think a 737 can take that???

Not a chance. That’s his ground speed - not his true air speed.

Ohhh. I didn’t think about the ground speed… Thanks.

Mach number as posted in FA is very misleading. It is some bizzare interpretation of the groundspeed of the aircraft, and about the most useless and misleading thing I’ve ever seen on FlightAware.

In short, NO the 737 isn’t going mach 1. I’ll try to keep this simple.

“Mach”, or the speed of sound, varies depending on altitude. At sea level, the speed of sound, mach 1, is 761 mph. To figure out what mach 1 is at altitude, you multiply the constant, 761 mph, by a conversion factor, seen on the chart below.

**Altitude in feet Speed of Sound ratio **
Sea Level 1.00
5,000 ft 0.9827
10,000 ft 0.9650
15,000 ft 0.9470
20,000 ft 0.9287
25,000 ft 0.9100
30,000 ft 0.8909
35,000 ft 0.8714
40,000 ft 0.8671
50,000 ft 0.8671
60,000 ft 0.8671

Using the supplied aircraft track as an example, multiply 761 by the conversion for 39,000 ft, approx 0.868.

761x0.868= 660 mph

So, at 39,000 ft, mach 1 is approx 660 mph.

Now, the groundspeed of the aircraft in question reached or exceeded 660 mph. That is to say that the actual airspeed and a tailwind component acting on the aircraft added up to 660 mph. The actual airspeed of a 737 is typically .72 to .76 mach or therebouts.

In over 20 years or professional flying, I have never seen groundspeed expressed in mach, and have no idea why someone decided to do it on here.

No problem. If you look at that tracklog for that fast Citation X thread in the Charters forum, you’ll see that he was doing mach 1+ for nearly the entire flight and we all know that isn’t possible either. They’re having a little help from the tailwinds. I wish though. Bring back the Concorde!

So that people can check the log of their commercial flight when they land and then tell everyone they broke the speed of sound! Why else?

I used to work at a feeder sector in eastern Canada and it wasn’t unusual have aircraft eastbount (lookling for descent) grounding at 620-630kts.
It was a bitch to get them down from 350 to 160 in 80 miles though!

Oh it’d do over Mach 1…but it’d be it’s last flight.

This one was truckin along pretty good, LAX to IAD in about 3 1/2 hours

638 kts
734 mph
1.11 mach

flightaware.com/live/flight/UAL9 … D/tracklog

Please don’t confuse Ground speed with true airspeed…

Not confused at all, the jetstream was crazy yesterday.

rap.ucar.edu/weather/upper/upaCNTR_250.gif

A pretty nifty website on this subject:

groundspeedrecords.com

Yep, one of my favorites!

Where in a 744 or a 738, show GS?

The GS will read out on the ND. As you can see the GS, TAS, wind speed and direction are located in the upper left hand corner.

projectmagenta.com/products/b/nd737.jpg

The jetstream still giving them fits. Today was the inaugural flight of US Airways’ new non-stop CLT to HNL on a B762, and it had to make a tech stop at LAX for fuel due to the strong headwinds.

Hey Will, here’s a 736 knot groundspeed on a 744, tailwind 240 knots yeah!

groundspeedrecords.com/photos/B744%20736kts.JPG

That site is cool, but how can you trust some of those numbers? Some of them, yes, I believe it, but a picture of a GPS unit only doesn’t prove anything - there’s no telling what is pushing that speed. 189.5 kts in an ultralight??? Next commercial flight I take, I’m going to smuggle on a little GPS, take a picture and break the record for the Cessna 152.

groundspeedrecords.com/records/r … 90ktts.htm

Edit: After looking at the link I posted, I don’t even see the GS listed on his screen (aka: the proof).

No need to smuggle it on - some airlines allow them. Southwest is one of them. On my last long distance trip with them I even used the holder and attached it to the window.

I have done the GPS on a Delta Flight too. The problem is the aluminum body does make getting a signal hard at times