Tampa Approach Control: “Cessna 30D, maintain 130 knots.”

How would you read back that clearance?
Here’s what the AIM says:
4−4−7. Pilot Responsibility upon Clearance Issuance
b. ATC Clearance/Instruction Readback.
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. The read back of the “numbers” serves as a double check between pilots and controllers and reduces the kinds of communications errors that occur when a number is either “misheard” or is incorrect.
What’s missing in this paragraph? There’s no mention of airspeed! I supposed you could argue that the AIM does include airspeed if you focus on its mention of vectors. Technically, vectors are a combination of direction and velocity. Although, the AIM provides this definition of vector in its Pilot/Controller Glossary.
“VECTOR− A heading issued to an aircraft to provide navigational guidance by radar.”
Um. So much for the heading and airspeed argument.
I guarantee you, if Tampa Approach says, “Cessna 30D, maintain 130 knots,” and you respond with your call sign only, Tampa Approach is going to insist on a readback of your speed assignment. Citing the appropriate passage in the AIM to the controller is not going to help your cause.
Fine, I’ll Read Back Airspeed Assignments
Tampa Approach Control: “Cessna 30D, maintain 130 knots.”
You: “Cessna 30D, 130.”
Good, right? After, all the AIM tells you to read back “the numbers”. Excuse me. I’ve got to go take some antacid for my AIM heartburn.
Okay, I’m back. The AIM says, “The read back of the ‘numbers’ serves as a double check,” blah, blah, blah. What the Government meant to say was, “The read back of the ‘numbers’ plus the applicable unit,” blah, blah, blah. Let’s put it in context.
Tampa Approach Control: “Cessna 30D, maintain 130 knots.”
You: “Cessna 30D, maintain 130 knots.”
Tampa Approach Control: “Cessna 30D, reduce speed to 110.”
You: “Cessna 30D, reducing speed to 110.”
Why Including a Unit is Important
I guarantee you, at some point in your flying career you’ll hear this radio exchange between ATC and another pilot:
ATC: “Lear 78M, turn right heading 180. Reduce speed to 170.”
Pilot of Lear 78M: “Lear 78M, 180, 170.”
Does that conform to AIM guidance? Yes it does. Is it a smart readback? I don’t think so. Will he turn to 180 degrees or 170 degrees? Will he maintain 170 knots or 180 knots? Who knows? A safe and coherent readback does not generate question marks.
The Takeaway
When ATC gives you an airspeed assignment, read back the number and add “speed” or “knots”. If the controller says “speed” include “speed” in your read back. If he says “knots”, read back “knots”. It only takes just a couple extra calories and a few milliamps of brain power to make one of those words come out of your mouth. The extra effort provides, as the AIM says, “a means of mutual verification.”
Good stuff? There’s more in my new book, Radio Mastery for IFR Pilots, available soon at Amazon.com.