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Citing the FAA from Airplane Flying Handbook

On the departure leg after takeoff, the pilot should continue climbing straight ahead and, if remaining in the traffic pattern, commence a turn to the crosswind leg beyond the departure end of the runway within 300 feet of the traffic pattern altitude

I am wondering why this would be the procedure, compared to something like standard distances (like a half-mile radius, which is a loose guideline in GA pattern spacing). Or maybe published ground references, like when there is a noise abatement procedure.

Seems like this suggestion causes a hot spot for collision where crosswind meets downwind. I have a real example from a controlled airfield.

tl;dr - A low power plane takes off just before a higher power plane. Both turn crosswind at 700' AGL and downwind at 0.5 miles. Near miss where crosswind meets downwind.

Busy class D airport. 2 Cessna 172's ready for departure. Call the first one 172A. I'm second in 172B.

172A is a 4 passenger 160hp. I'm in a 180hp solo. During run up I hear 172A for straight out departure (this is wrong, I heard incorrectly). I'm a right downwind departure. 172A is cleared for takeoff. I line up and wait. Then my 172B is cleared for takeoff. There is a thick cloud layer 2 miles out at 1000 AGL. I climb to 700' AGL and about 10 seconds into my crosswind turn, 172A appears above near the cloud layer flying directly at me, about 100' above, 500' away. The cloud layer is close ahead (not risking VFR to IMC), and there's a busy class B less than a mile out crosswind, so I round out to downwind early, stay to the right of their track, full power to remain ahead, but pitch level to stay under their track incase they have much higher speed.

I ask traffic on downwind if they see me, and tower comes on screaming that I've cut off downwind traffic, and to increase speed and leave their airspace. They thought I was trying to save myself time, but I thought I was just flying my pattern. Funny thing is, so did the pilot in 172A.

I could have:

  • Listened better to #1's departure clearance and kept him in sight
  • Asked for more spacing or clear my crosswind since it was a close departure anyway

ATC could have:

  • Spaced us more
  • Call my crosswind

ATC didn't notice me on crosswind until after, but I don't believe ATC was being lazy, they were probably just dealing with inbound traffic or ground. I did later ask them where is a good point to turn crosswind, but they said that's not how it works and I should read the rules. I did, seen above. I met with the other pilot afterwards, and he said the same thing, just flying the standard pattern.

I'm worried that I'm still the idiot here, but I just want to put this out there for consideration and public review in case there is more to learn here.

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    $\begingroup$ Lots to unpack, but a note up front: in Class D there is no minimum separation (no set distance) which ATC must ensure between two airborne VFR aircraft. However ATC must issue traffic advisories and safety alerts as necessary, and must ensure proper runway separation; for two departing C172s the minimum is #1 is 3000' down the runway and airborne when #2 begins takeoff roll. $\endgroup$
    – randomhead
    Jul 26, 2022 at 2:56
  • $\begingroup$ It seems what happened here was your groundtrack was to the right of the other plane on departure. You also may have been climbing faster. It might have helped to maintain sight of A while climbing if possible. In spite of being yelled at, your actions may have prevented the situation from getting alot worse. $\endgroup$
    – Robert DiGiovanni
    Jul 26, 2022 at 2:58
  • $\begingroup$ @RobertDiGiovanni in this case, ground track was mostly straight for both if I recall correctly. It was a few seconds into crosswind at first visual contact. But groundtrack is also a variable in this crosswind-downwind hotspot. $\endgroup$
    – user
    Jul 26, 2022 at 5:29
  • $\begingroup$ IF 172A is a straight out departure I would not expect them to turn downwind and leave the airport that way. It seems (1) either I heard the radio incorrectly or (2) 172A did something they did not say they were going to do. $\endgroup$
    – wbeard52
    Jul 26, 2022 at 5:33
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    $\begingroup$ Bottom line, is you were VFR. YOU are responsible for aircraft separation. Maintain visual contact with the aircraft ahead of you. If you lose sight tell the tower controller, (or if uncontrolled, tell the other aircraft), (172A, this is 172B behind you, crosswind at 700 AGL, I have lost sight... Say your position and altitude.) $\endgroup$
    – Charles Bretana
    Jul 26, 2022 at 12:39

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compared with standard distances ... or published ground references

As one can see, all of these help maintain separation.

Strictly adhering to "turn crosswind when within 300 feet of pattern altitude" has one obvious flaw, an aircraft with a higher rate of climb will turn sooner.

Plugging in some numbers, one is climbing at 400 feet per minute and the second at 700 feet per minute. With 1/2 mile separation at take off and similar Vy, we can see that the second plane turns almost at the same time as the first. With no established distance for the cross wind leg, the second plane will turn inside the first.

If the second plane turns a wider radius, and both are trying for the same altitude, they may be on a collision course.

Without references for the crosswind leg being a certain distance from the runway, yes, this could lead to a potentially dangerous situation.

As stated in comments, it is important not to lose sight of the plane ahead of you. You might have been able to stay outside the A track from the start and climbed with a bit less power to maintain separation. (It is understandable you didn't, thinking they were departing straight out),

The "turn when within 300 feet of pattern altitude" rule is just part of a much bigger safety picture.

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