3
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I would like to know how does the speed of an airliner vary as a function of time.

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Ballpark:

  • At the gate, 0 knots
  • Taxi, 5-30 knots (usually 10-20)
  • Takeoff, 150 knots (rough ballpark)
  • Climbout below 10,000', 250 knots
  • Climbout above 10,000', 270-320 knots
  • Climbout above 28,000', Mach .78 (ballpark)
  • Cruise, Mach .78 (groundspeed ~450 knots +/- wind)
  • Descent above 28,000', Mach .78
  • Descent 28k to 10k, 280 knots (up to 330 knots, if ATC requests)
  • Descent below 10k, 250 knots
  • Traffic pattern,200 knots
  • Final approach, 140 knots
  • Taxi in, 10-30 knots
  • At the gate, 0 knots

Edit: these are fairly typical 737 numbers; other aircraft will have differences. Regional jets will typically be slower; 747 and 777 will often be faster (especially for takeoff and cruise).

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  • $\begingroup$ Cruise: 0.78 only? I've got figures above 0.8 in my mind, but I'm not totally sure. $\endgroup$ – user7241 Dec 10 '17 at 15:02
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    $\begingroup$ @jjack Mach 0.78 is within the usual range of cruise speeds for at least some common aircraft types, but something over Mach 0.8 could occur too. See the charts under Cost Index-Cruise Speed Relationship in ansperformance.eu/references/library/airbus-cost-index.pdf for example. $\endgroup$ – David K Dec 10 '17 at 15:20
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    $\begingroup$ At the two 747-100/200 carriers I worked for, cruise was 0.86. Management at both companies advocated for 0.84, but both elected for cost reasons not to maintain the autothrottle systems that made that easy. Trying to maintain 0.84 manually was a seesaw operation that flight engineers might try for awhile. The easy thing to do, and which almost everyone did, was to select a power setting that put the airplane at 0.86, where it would stabilize (due we felt to a drag rise there) and not require continual adjustment. $\endgroup$ – Terry Dec 10 '17 at 19:25
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    $\begingroup$ @Terry: That worked well when fuel was 50 cents per gallon. $\endgroup$ – Peter Kämpf Dec 11 '17 at 20:58

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