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wmantly t1_itqst46 wrote

Doesn't commercial airlines fly at like 500mph?

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Jonathan924 t1_itquttq wrote

The rest of the plane acts like a crumple zone, slowing down the recorder before it suddenly stops.

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wmantly t1_itquzxc wrote

Unless it blows up, then there isn't much to crumple...

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runtscrape t1_itqxhqt wrote

In a breakup it would hit the ground at terminal for the chunk it's a part of, which would be much less aerodynamic than the whole aircraft.

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[deleted] t1_itqttw7 wrote

[deleted]

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way2funni t1_itr9i0c wrote

>cruising at a cool 700mph

likely due to the jetstream effect throwing off the numbers.

you were probably in the polar jet which can reach speeds of up to 275 mph and runs west to east so if you were going TO EU, the effect of this tailwind could have easily boosted your speed 'across the ground' (which is what the SATNAV systems report) to 700 mph without any sound barrier shenanigans but 'airspeed' relative to the surrounding air was probably 500-550 which is standard cruise these days to conserve fuel.

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small_giant t1_itqz8s9 wrote

Now that I think about it, I took crap at 700 mph!

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guitarnoir t1_its7xjb wrote

"Did you just hear a giant fart?" "No, that was just a sonic boom--we're doing 700mph!"

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48for8 t1_itqujzz wrote

Sure that wasn't kilometers? Flights usually average 500 mph...either way still way above 310

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[deleted] t1_itqv0w2 wrote

[deleted]

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Poop_Tube t1_itr2052 wrote

Yes I believe it if it was with a tailwind. The air around them was moving 150-200mph so the plane relative to the air was below 500mph, not breaking any sound barrier.

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friedmators t1_itr0wcs wrote

Airspeed might be 150 less if you were with the jet stream.

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[deleted] t1_itr0t97 wrote

[deleted]

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way2funni t1_itrd1bi wrote

> The speed of sound is around 660mph

true but the jetstream going US to EU is doing a lot of that lifting to get a 700mph readout on the SATNAV system..

700 mph 'across the ground' can also and at the same time be 550mph 'airspeed' when you surf the polar vortex going west to east.

Even though the aircraft is moving at 700mph across the ground, there is no sonic boom or breaking of the sound barrier which requires the aircraft to break 660mph in airspeed.

The polar jetstream tailwind is no joke. It's how/why the typical NY to London flight time is approx 7 hours and London - NY is 8 hours +

They take advantage on it going to London and try to avoid it as much as possible when going back to NY.

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wmantly t1_itqtze0 wrote

That's what I'm saying, 310mph seems way too little.

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Brandon432 t1_itqvsci wrote

There is almost no chance the flight recorder comes to an instantaneous stop. The plane is going to crumble, so is the ground.

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Ishidan01 t1_itr1z7o wrote

Yes, but cruising speed is also very far from anything to crash into.

At a closing speed of 1,000 mph, a head on collision wouldn't leave much on the recorder anyway- you wouldn't have time to speak between perceiving the oncoming and impact.

Plane just disintegrates? Engines gone so thrust lost, what's left falls by gravity against wind resistance, so what is terminal velocity for a powerless fuselage?

Otherwise, most crashes will be at lower speeds, as the pilot tries to soften the impact with whatever slow-down ability is left.

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popsickle_in_one t1_itr2h7w wrote

In theory, most pilots won't crash their planes at full speed.

In practice, almost every crash happens close to take off or landing, and the plane is flying slower than cruise speed. A lot of crashes come from stalling the plane, which also lowers the speed of the eventual lithobraking manoeuvre.

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