For aircraft cruising along at altitude, it is common for the controller to assign an aircraft a new course or altitude or speed for some reason such as "for traffic". My question is, would most turbojet/turboprop pilots rather have a vector, say 20 degrees off course for 10 minutes, or have a different altitude, or have a speed assignment? What is most efficient for the airplane? Do companies have a preference? Are certain actions easier for the pilot? I suppose there is a fuel-use vs. time-en-route trade off in some cases, and many other factors as well, and personal preferences might vary widely, or maybe people don't really care?


2 Answers 2


If ATC offered me a heading change or an altitude change and I was happy with the altitude I was at, I'd take the heading change in a heartbeat. Compare:

Altitude change:

  1. Dial the alt preselect up.
  2. Select speed or VS mode (usually speed).
  3. Set climb thrust.
  4. Monitor the capture.
  5. As the AP captures and pitches over, start bringing the thrust back to keep from speeding up until the original thrust setting is restored.

Heading change:

  1. Select Heading Mode if in Nav mode. If on vectors, it's already set.
  2. Twirl the heading bug and monitor the turn.
  3. When told to, dial the heading bug to a new heading as instructed or to a suitable intercept angle and reset Nav mode if told to resume self navigation.

Notice that with the heading change I don't have to screw around with power, which can be more hassle or less hassle depending on if you have FADEC, but in any case a lot more work than twirling the heading knob and pushing a button.

  • $\begingroup$ Not to mention the fuel savings of staying at altitude. That's the biggest factor in my mind. $\endgroup$
    – J W
    Sep 18, 2018 at 11:37

There are a few kinds of traffic advisories but generally pilots don't (and can't) have a preference at least not one they can generally act on. Keeping routes as short as possible and staying on time is what any pilot wants but you cant always get what you want!

Those that come from TCAS require a quick climb or dive and preference is irrelevant you do what the system says.

As for ATC routing changes are expected, you are required to follow them, and generally there is no preference. For traffic alerts under VFR flight following you may get a

Turn right 20 degrees for climbing traffic

This is a fairly benign maneuver and generally you will get some kind of return on course not to long after. Turning left or right is all the same and on anything bigger than a GA plane its likely handled by the turn of a dial on the auto-pilot.

In crowded terminal approach areas changes, and quick ones, are to be expected. Pilots cant really have a preference as they don't really have a full picture of whats going on. ATC is there to route planes, not suggest what they should do. If you want a bit of an over dramatic representation I would advise watching Pushing Tin if you want some real examples there are lots of videos out there of the real thing and you can stream it here if you want to hear it in real time.

Weather diversions are a bit more complicated especially in aircraft that are equipped with weather radar. When it comes to weather diversions ATC has a lot of info but the aircraft may have actual situational info. In this case the aircraft can request a diversion if they see something crop up and ATC may issue advisories and make a diversion available. In this case the pilot may have some preference based on what they are seeing on their onboard radar.

Fuel usage is something to consider any time a diversion is issued. Generally pilots can not denny a diversion but no pilot should willingly create a dangerous situation and diverting without taking fuel into account is potentially dangerous.

  • 1
    $\begingroup$ Why should pilots have no preference? What you really mean is that pilot's preference for traffic resolution is not relevant. $\endgroup$
    – bogl
    Oct 3, 2018 at 12:28

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