It’s obvious that helicopters and fixed-wing aircraft operate differently. But pilots are sometimes unaware of what that actually means for safe flying in the unattended aerodrome circuit.
Risk doesn’t result only from deliberate rule-breaking. It also comes from misunderstandings which lead pilots into making incorrect assumptions.
CAA Investigator Jason Frost-Evans, an experienced helicopter and fixed-wing pilot, says the core issue is that, “Sometimes pilots of one type of aircraft aren’t particularly familiar with how other aircraft operate”.
That can lead pilots to misjudge the speed, profiles, and manoeuvring of other aircraft – and where they should be. This, coupled with a high workload, or distractions during a busy phase of flight, can lead to conflict in the circuit.
A near collision at Rangiora in 2024 shows how quickly this can happen.
A helicopter was lifting to depart while a Cessna began its take-off roll, each pilot assuming the other had already cleared the area. The aircraft converged at low level, missing each other by seconds. Incomplete radio communication and ineffective visual scanning meant the pilots formed the wrong impression about each other’s position and intentions.
Events like this often stem from how helicopter manoeuvres appear to other pilots in the circuit.
Surprising manoeuvres
The differences between helicopter and fixed-wing manoeuvres become most obvious during helicopter training. These can surprise fixed-wing pilots unfamiliar with them, Jason says.
“It’s important other pilots understand the rotary pilot’s terminology, and what it means for how quickly and tightly a helicopter manoeuvre can unfold.”
Autorotations
If you hear a helicopter pilot say on the radio that they’re about to undertake a ‘practice autorotation’, here’s what’s about to unfold – the helicopter will descend without engine power, simulating an engine failure. The upward airflow through the rotor keeps it turning so the pilot can control the descent and flare to land.
Autorotations are essentially a glide approach but are much steeper and with a rate of descent between 1500 to 3000 feet per minute.
Because the helicopter will normally remain at circuit altitude until the landing target can be reached, it can look like the helicopter has started a go-around – until it suddenly descends quite rapidly.
A variation on this is the 180-degree autorotation. It’s initiated downwind, quite close to the aerodrome, and involves a 180-degree turn-back towards the target spot.
Quick stops
A quick stop is a manoeuvre where the pilot progressively slows the helicopter from forward flight to a hover or near-hover, usually at low level. Jason says training on these manoeuvres takes up space and can look quite aggressive to pilots who don’t recognise them as carefully controlled exercises.
As well as these set-piece manoeuvres, trainee pilots, in particular, spend a lot of time practising hovering in the infield. For fixed-wing pilots, it can seem unclear what may occur next.
“It’s happened to me,” says Justin Smith, Chief Flying Instructor at Kāpiti Aero Club. “I’ve been waiting on the runway, watching the helicopter and not sure what it will do next.
“That’s when it’s a good idea to radio the helicopter pilot and check what their intentions are.
“Don’t assume, don’t take a chance, just get on the radio and ask them.”
One crucial difference
Jason Frost-Evans says one simple distinction explains many mixed-circuit conflicts – helicopters typically stop and then land, while aeroplanes land and then stop.
While that might sound like stating the obvious, this difference has significant effects on spacing, sequencing, and closure rates. An aeroplane following a helicopter can close the gap more quickly than expected.
If either pilot doesn’t appreciate how quickly that spacing can change, uncomfortable or unsafe situations can develop rapidly.
Justin Smith says other pilots – including students – get caught out by this.
“On occasion, I’ve had to grab the base radio and advise a student they’re getting close to where a helicopter is operating. The student’s concentrating on what they’re doing, maybe not understanding or not correctly interpreting where the helicopter will be.”
Circuits rely on shared understanding
Circuit patterns are designed to facilitate an orderly flow of traffic, but they work best if pilots understand how different aircraft climb, descend, accelerate, and manoeuvre – especially when they’re close to the ground.
Helicopters may be slower in forward speed during final and upwind, climb and descend on a steeper profile, and may operate lower in the circuit.
Justin says he’s been caught out by this while flying in Hawke’s Bay.
“I’ve done it myself, flying IFR in and out of Hastings aerodrome at Bridge Pā, which I’m very familiar with.
“A helicopter radios that they’re flying in from the west. I’ve drawn conclusions about where they will be, then I come out of the cloud and they’re a lot closer than I’d thought.
“I should have been thinking about what altitude they would be at and what stage of their flight, not just the direction they were coming from.”
Radio calls aren’t enough
Radio calls are essential if the aircraft is equipped, but they’re only one mitigation for potential conflicts.
Helicopter calls should aim to tell other pilots what will happen next, not just where the rotary aircraft is, at that moment.
And simply announcing an impending manoeuvre isn’t enough, either. Helicopter pilots need to make sure their actions don’t create problems for other traffic, including forcing fixed-wing aircraft into go-arounds or their pilots having to make last-minute decisions.
That means using plain language – including clearly stating direction of approach, altitude, and making use of visual reporting points.
Jason Frost-Evans says helicopter pilots need to anticipate where confusion might arise. They should time their training manoeuvres carefully, planning them to fit into gaps in traffic wherever possible so other aircraft are not unduly affected.
All pilots in visual conditions need to back up radio calls with deliberate visual scanning and, when needed, timely follow-up calls to confirm what’s happening in the circuit.
It’s also important for fixed-wing pilots to understand that helicopters don’t always use the circuit, and that’s often a conscious safety decision. They may approach from different directions, cross the runway at low level, or operate elsewhere in the aerodrome.
If pilots scan only where traffic should be in a standard circuit, they risk missing helicopters that are intentionally avoiding the circuit.
Checking the AIP before flying at an aerodrome can reduce uncertainty. Have a look at the circuit procedures, helicopter operating areas, preferred approach paths, and any local differences you might not expect.
“It gives pilots a clearer mental picture of how fixed-wing and helicopter traffic is likely to operate. Then it’s easier to interpret radio calls, anticipate movements, and avoid misinterpretations that can lead to conflicts,” Justin Smith says.
Beyond training manoeuvres
Autorotation training is the most conspicuous of a wide range of helicopter operations that can surprise other pilots. But there are others.
Helicopters may fly tighter circuits, steeper profiles, conduct straight-in or short-final training autorotation approaches. They may spend extended periods operating at low level within the aerodrome in ways that – from a fixed-wing perspective – look unconventional and unpredictable. But they are normal, and planned.
The bottom line
Standard circuit procedures are important for predictability, but pilots still need to be vigilant for circumstances that require flexibility, including taking account of how helicopters operate.
In mixed operations, understanding the other aircraft type isn’t optional – it’s a vital part of staying safe.
More information
Vector Online: Near collision at Rangiora
Watch the Good Aviation Practice video ‘Circuit Certainty’. It’s part of our Work Together Stay Apart resource library.
Footnote
Main photo: iStock.com/NCHANT