Rule breaches are among the most common factors in mid-air collisions or near collisions.

There are four fundamental rules underpinning safe flying around unattended aerodromes:

“These four rules really offer an unattended aerodrome ‘road code’,” says Aaron Pearce, of the CAA’s Work Together, Stay Apart campaign.

“The rules aren’t there to ruin our ‘fun’ or limit what we can do. They’re there so we all know how the traffic will flow, how each of us will behave, and what each of us will do.”

“These four rules all have one commonality – avoiding conflict,” says CAA Aviation Safety Advisor Carlton Campbell.

“It’s significant that in each of the three most recent mid-air collisions in New Zealand, at least one of those four rules was breached.”

The Transport Accident Investigation Commission (TAIC) has noted that, of the 12 mid-air accidents in New Zealand from 1988 to 2008 – in which 20 people died – half were at, or in the vicinity of, unattended aerodromes.1

It should be noted that the pilots involved in New Zealand’s three most recent mid-air collisions were all at their home aerodromes.

“I would say that if every pilot at an unattended aerodrome – including at their home aerodrome – flew as those four rules intended, and coupled that with a reasonable level of situational awareness, there would be no mid-air accidents and no close calls,” says Aaron.

Rule 91.127 Use of aerodromes

This basically says we must operate in accordance with the aerodrome operator’s procedures, including the published circuit direction. Why? It’s probably kind of obvious, but here it is – it makes your aircraft’s flight path predictable to other aircraft, as theirs will be to you. No nasty surprises.

Rule 91.223 Operating on and in the vicinity of an aerodrome

Rule 91.223 mandates the requirement to adhere to the published and established circuit (and, if transiting, to avoid conflict with circuit traffic).

During its investigation into the 2019 mid-air collision in Masterton, TAIC found that one of the pilots was joining a non-standard right base for a left circuit runway.

The TAIC report noted, “The non-standard join was at variance with civil aviation rules, but had become an accepted practice at the aerodrome”.

“Standardised procedures ensure that we’re all doing the same thing,” says Aaron. “They make us predictable to students, itinerant pilots, and pilots who don’t fly very often. They aid traffic flow and help with sequencing. They’re also our go-to in an emergency.

“And in New Zealand, we have NORDO (without radio) aircraft, so standard procedures are the only way to separate, and spot the aircraft that aren’t transmitting on the radio.”

Rule 91.223 also repeatedly states the requirement to observe other aerodrome traffic for the purpose of avoiding a collision.

Research2 from the FAA found that “inadequate visual lookout – failure to see and avoid” – was the most common cause of mid-air accidents.

Interviews between the FAA and 658 pilots who survived a mid-air collision found that 88 percent of them never saw the other aircraft before they collided. The remainder saw the other aircraft, but too late to initiate avoiding action.

The TAIC investigation of the 2008 Paraparaumu collision found that, “…the three pilots had probably been concentrating on flying their aircraft and planned manoeuvres to the detriment of listening and maintaining an effective lookout”. (Vector emphasis)

“Lookout is the fundamental principle of safe flying at all unattended aerodromes,” says CAA Flight Examiner Katrina Witney.

“When all else fails – poor, or no, radio calls, non‑standard procedures, or misjudged reliance on tech – an excellent lookout by even one pilot will literally save lives.”

Rule 91.227 Operating near other aircraft

This rule says, “A pilot must not operate an aircraft … so close to another aircraft as to create a collision hazard”.

“But we do see pilots who ‘push’,” says Aaron Pearce.

“Why continue in the direction of, or at a high rate of speed towards, unsighted known traffic? Not only are you not avoiding conflict, you’re actually, clearly, creating it.

“No pilot has the right to unheedingly reduce another’s safety margins.

“Fly defensively – that doesn’t mean aggressively. It means maintaining a safety bubble around ourselves, and not rushing or encroaching on each others’ bubbles.”

Rule 91.229 Right-of-way rules

“If an aircraft has right-of-way, the responsibility of spacing in the circuit is on the following aircraft,” says Carlton Campbell.

“Give each other a little breathing room. You don’t know what’s going on in the cockpit ahead of you. Maybe it’s someone’s first flight after a break, or maybe it’s a student whose lesson hasn’t gone as well as they expected.

“We all need to be patient, stick to the standard, and realise we’re all human, and all make mistakes, especially early in our flying.

“You cannot overtake in the circuit – although this doesn’t prevent ‘number one’ yielding their position to the following aircraft if circumstances allow.”

Rule 91.229 also says that, “A pilot who has the right-ofway must maintain heading and speed, and is not relieved from the responsibility of taking such action, including collision-avoidance manoeuvres … that will best avert collision”.

“It’s been seen and reported that some pilots have tried to take advantage of the right-of-way rules,” says CAA Flight Examiner Brendon Bourne.

“They race onto a circuit leg, or from the non-traffic side, to take the number one position, again causing potential conflict.

“But what have you achieved in getting so close to conflict? A few seconds off your journey? Getting to be ‘number one’? Is it really worth it?

“Everyone wants to get home safely, and because we share unattended airspace, that means looking after each other.”


This article is a summary of the key points in these rules for avoiding conflicts at or around unattended aerodromes. It doesn’t cover everything that’s in the rules. For maximum safety, take time to read and truly understand all these rules, and apply them every time you fly.



1 The other half were either planned close proximity flights, like formation flights, or company aircraft working together.

2 FAA Aviation News, May/June 2000.

Posted in Aerodromes, Pilot performance flying practice and professionalism, General safety;

Posted 5 months ago