Which ATC instructions should be repeated back by the pilot?

Question

AIM 4-4-7 (b) says:

Pilots of airborne aircraft should read back those parts of ATC clearances and instructions containing altitude assignments, vectors, or runway assignments as a means of mutual verification.

As a student pilot soloing into class C airspace, on one flight ATC kept repeating everything back until I spoke it back to him. As I approached the airport he informed me of the bearing (12 o'clock) and distance to the airport until I acknowledged him (comms were pretty busy so I didn't initially repeat back his information).

Since then I've noticed that if I don't repeat back wake turbulence warnings verbatim they will repeat the warning until I do. With a traffic alert I repeat back immediately 'looking for traffic' because if I look first they'll keep repeating the warning.

Aside from AIM 4-4-7 is there any more specific guidance?

Answer 1

ATC is, broadly speaking, required to ensure that pilots hear, understand, and acknowledge information that is delivered. The way they do that is via read-backs, and although the AIM mentions a few of the things that are required it's a good idea to read back anything that's important (If you're not sure, err on the side of "It's important"), with your aircraft callsign (No callsign? Doesn't count!).

What are some important things controllers usually expect you to read back?

• Clearances (headings, vectors, altitudes, transponder codes, and radio frequencies).
  Like the AIM says, mutual verification.
• Runway assignments, hold short instructions, line-up-and-wait, and takeoff clearances.
• Taxi routes Instructions, ESPECIALLY runway crossings & hold-short instructions.
• Wake Turbulence advisories.
• Traffic point-outs.
  The magic words here, by the by, are "Negative Contact" and "Traffic In Sight".
  ^{I think if you say "Tally Ho!" you're required to buy everyone on the frequency a bottle of 30-year-old scotch.}
• Instructions to "Maintain visual separation with" some traffic
  ATC is handing off collision avoidance responsibility to you as the pilot.
  They need to hear "Will maintain visual separation with" the traffic in question.
  They also need you to tell them if you lose visual contact.
• Airport Point-Outs (Especially if there are several airports close to each other)
  You can also pre-empt this by calling the controller: "Cessna 12345 has Podunk Municipal in sight", possibly with a bearing and approximate distance.
• Landing Clearances
  If you're in a busy pattern and they give you a sequence ("Number 3, cleared to land") they want to hear that part too.
• That altimeter setting you get after a handoff.
  (I blame Don Brown for getting me into this habit, but it IS a good one unless the frequency is crazy)

This list is by no means exhaustive, but it's most of the big stuff.

Answer 2

This little quote from the AIM is the source of a lot of confusion for new pilots.

In 4-2-3 (c), the AIM also says:

c. Subsequent Contacts and Responses to Callup from a Ground Facility.

You should acknowledge all callups or clearances unless the controller or FSS specialist advises otherwise.
...
Acknowledge with your aircraft identification, either at the beginning or at the end of your transmission, and one of the words "Wilco," "Roger," "Affirmative," "Negative," or other appropriate remarks; e.g., "PIPER TWO ONE FOUR LIMA, ROGER."

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Let me make it simple:

• You should read back those items that the AIM 4-4-7 specifies (and that you quoted in your question). Basically any time that they give you a clearance or anything that contains a number.
• You should acknowledge with at the bare minimum your aircraft call sign and preferably something that lets them know that you got their instructions/message and understand it, every time that ATC talks to you.
  
  • The one exception is after you have been handed off to the final controller on a PAR approach, you do not acknowledge their instructions. They come too fast and you will have your hands full (and they specifically tell you this after your initial contact.)

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As a short aside, you should know that there is case law which says that even when a pilot reads back a clearance incorrectly, the controller is not legally obligated to listen or correct the pilot. They consider it the pilot responsibility to hear and understand all clearances. For instance:

Controller: Cessna 1234, descend and maintain 3,000 feet
Pilot: Cessna 1234, Roger, descend and maintain 2,000 feet
Controller: No response
Pilot: Descends to 2,000 feet because that is what he understood, and may now be violated for it.

That being said, most controllers are very good and catch mistakes like this that you may make, but I have heard conversations in the cockpit along the lines of "it must be right because they didn't correct me when I read it back" and this is a situation ripe for problems/violations. If there is ever a doubt, ask for clarification!

Answer 3

Regardless of what the AIM says, the practical rule I've always been taught is "read back all instructions". In other words, if ATC is telling you to do something then you must read it back otherwise they have no way to know if you understood the instruction correctly and will do what they expect you to. This includes clearance, ground and airborne instructions.

ATC information on the other hand is not an instruction (e.g. traffic advisories) so you only need to acknowledge it. But you should also read back altimeter settings because they're essential for maintaining altitude and therefore separation correctly.

And ATC is often very good at giving student pilots extra attention so even if they wouldn't expect a readback in other circumstances, they may have made an extra effort in the case you mentioned to make sure there was no possible misunderstanding.

Answer 4

Not really an answer per-se, but I usually find it much easier to learn what NOT to read-back:

• Weather information (except QNH (altimeter settings)), like wind speed/direction, etc
• Time/hour/estimates (except EAT (expected approach time) when cleared to a hold)
• Chatter (hey, it happens! don't read it back)

I can't seem to think to any others, though there should be a couple more. Anything else that doesn't fall into this will get a readback from me.

Answer 5

The answers here are correct. Just adding my perspective as a controller.

• Runway hold short instructions. This is a required readback item. Super-high priority. We need to hear three things in one single transmission: "Hold short," the runway number, and your callsign. All three. In one transmission. We need it.

• Runway assignment. This isn't quite as strong as the hold-short readback, I think it's still required but I personally won't be on your case quite as much about it. In any case I think you're supposed to read it back.

• Visual separation confirmation. In order to use pilot-applied visual separation between IFR aircraft, we need to: 1) tell you about traffic, 2) hear you say "traffic in sight," 3) tell you "maintain visual separation," 4) hear you say "wilco" or "will maintain visual separation," and 5) hear your callsign in that same transmission. You can combine a step by saying "traffic in sight, will maintain visual separation, [callsign]." Another 100% required readback situation. Note: If you, as a VFR pilot, call traffic in sight, we assume you will maneuver so as to avoid crashing into them because that's what the FARs say you have to do. See and avoid. I won't tell a VFR pilot to "maintain visual separation" unless it's for wake turbulence and even then I kind of feel like it's extraneous.

Everything else is not required on our end, but come on, it's good to make sure we're on the same page.

• Numbers. Altimeter, altitude/flight level, speed, heading, frequency, squawk code, etc. Common sense, I want to make sure you heard what I think I said, especially when it's a number and there's no context telling you a specific number would be right or wrong. Exception: wind check. You can read back the wind if you want I guess, but I'm not expecting you to.

• Instructions. Pattern entry/extension, 360s, S-turns, taxi route, hold-position, follow, pass behind, route amendment (shortcut or reroute), etc. You can be judicious about reading back the instruction vs saying "wilco" based on frequency congestion, complexity of the instruction, etc—but it's good to say something so we know you heard.

• Information/establishing two-way comms. Situation: You take off VFR, get switched to the departure controller, check on. Departure controller says "Radar contact" with no other instruction. Situation: You're on flight following and get a frequency change. You check on, "Podunk Approach, N12345 level 4500." Controller says "N12345, Podunk Approach, Podunk Altimeter 29.92." In either situation, have you established two-way communication? IMO, no!, you haven't yet! Please respond with something, even just your callsign, so each person knows the other party can receive their transmissions!

• Traffic. If we call traffic it's for a reason. Usually it's because we judge that you might get too close to that traffic. (Sometimes we have to call traffic even though we have minimum vertical separation so you don't freak out if TCAS freaks out.) It's not a problem if you don't have the traffic in sight—if we need to we'll issue control instructions to keep you apart—but you should at least respond with "looking" or "negative contact."

• Vectors to final. Essentially this is a specific case of the "numbers" and "instructions" bullet points. If you're getting vectors to an instrument approach, you will at some point hear "PTAC"—Position relative to apch fix, turn (heading) to intercept final apch course, altitude to maintain until established, clearance to fly the approach. This may be in one transmission or may be broken up. You definitely don't have to read back the position, and you might choose not to read back the heading and altitude (though I recommend it), but you should at least confirm that you understand you're cleared for the approach.

Basically there are extremely few situations where I am happy hearing zero response from a pilot. I don't need a full readback except for the three situations at the top of the post, but I don't like giving an instruction and hearing zero acknowledgement.