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the gremline digest — orbits in the visual circuit
Orbits in the Visual Circuit
The visual circuit at many GA airfields is a place of confusion that sometimes degenerates into chaos. The basic cause of this potentially dangerous state of affairs is a lack of uniformity in what the average GA pilot considers to be a “normal” visual circuit. This is probably brought about by lack of consistency in basic training and a lack of airmanship by the pilots concerned. The situation is no better at regional airports where commercial traffic and recreational traffic share the same circuit pattern. It is a sad state of affairs when an Air Traffic Controller has to take control of a GA aircraft in the visual circuit so as to integrate it with other traffic approaching the same runway.
Our article To Extend Downwind or Not To Extend? has, as intended, provoked some discussion within the recreational aviation community. I had a quite aggressive reaction from one Air Traffic controller (and GATCO Representative) who objected strongly to my inference in that article that I would decline an Air Traffic request to orbit in the visual circuit or to extend my downwind leg. He said he would complete the necessary ATC infringement form and stick it up my rear! He did not seem to accept the rules that actually apply to visual circuit traffic.
As I have emphasised in many accident reviews based on AAIB investigations, AAIB reports do not apportion blame or liability. Apportioning blame is not productive but it is sometimes useful to look at all the links in the causal chain of an accident with the aim of removing one of those links and thereby preventing the recurrence of a similar accident. Each of us must draw our own conclusions from the excellent AAIB Accident Reports, all of which are available at www.aaib.gov.uk.
I believe the following accident report adds weight to my contention that orbits in the visual circuit can be unsafe.
Rockwell Commander 112
A Rockwell Commander 112 had undergone an annual inspection at Exeter Airport. The pilot decided to fly a couple of circuits at Exeter before departing for Berry Head. This was a wise decision as he had only flown one hour in the previous 90 days. On the first circuit the pilot was asked by Air Traffic to orbit right when halfway down the downwind leg. He was eventually given clearance to continue after he had completed three orbits and he completed the visual circuit without incident. On the second circuit he was again asked to orbit to the right, but this time at the beginning of the downwind leg as checks were started. Clearance to continue was given after three or four orbits (i.e. about 6 to 8 minutes) and the pilot requested a full-stop landing. Unfortunately the pilot omitted to lower the landing gear and the aircraft scraped to a halt on the runway. The three occupants were unhurt.
The pilot commented that he had not heard the landing gear warning horn because he was wearing noise-cancelling headphones. It is probable that he did not lower the landing gear because the downwind checks were unwittingly interrupted by the ATC request for yet another series of orbits in the visual circuit. Flight Safety preaches that interrupted checks should be restarted from the beginning so as to avoid missing any of the critical items – such as lowering the wheels.
I accept that controllers are often faced with the difficult problem of integrating commercial traffic on an instrument approach with recreational traffic on a visual circuit. It is proper that, in most circumstances, the instrument traffic is given priority. My contention is that orbits in the visual circuit are potentially unsafe as they inhibit lookout, lead to mental confusion as to spacing with other traffic and can generate an expanding visual pattern.
I believe that we, pilots and controllers, need to look for a safer solution. There seems to be a confrontational attitude developing between some GA pilots and some air traffic controllers. This is unhealthy. I am not suggesting that this is the case at Exeter Airport, but I know it’s true elsewhere.
During my 50+ years as a military and civilian pilot, Flight Safety specialist and OC Operations at a military Master Diversion Airfield, I have tried to have Flight Safety hazards recognised and eliminated. I helped to have the three-needle altimeter eliminated from military cockpits. I would like to see orbits in the visual circuit removed from normal ATC operational procedures.
Response from SATCO Exeter
A draft review of the above accident was sent to the Senior Air Traffic Control Officer (SATCO) at Exeter International Airport for his views and we have received the excellent response that is reproduced verbatim below.
Dear Mr Stewart-Smith
Thank you for your recent correspondence and the opportunity to have an input to important safety related matters. To enable Air Traffic Control to integrate aircraft with the huge diversity of performance, vortex wake and flight crew experience within the circuit pattern at Exeter, it is crucial that the aerodrome controller has as many tools at his/her disposal to integrate traffic safely and of course expeditiously.
In my experience, the orbit has and will remain one of these tools if GA is to continue to operate in the increasingly busy regional airport environment. I believe the key in this instance rests with:
1. High standards of pilot training to include all those events likely to occur in a busy circuit pattern.
2. Ensuring interrupted checks are started again.
3. As you point out in your correspondence, discourage noise cancelling headsets.
I have to make clear my feelings that ATC in no way contributed to this accident. Here at Exeter, relations with the GA community are sound. Exeter has a high proportion of GA movements, much of it pilot training. It remains our goal to provide a safe, expeditious customer focused service to all who use our busy skies.
Senior Air Traffic Control Officer.
Noise Cancelling Headsets — again!
When I reviewed a fatal spinning accident to a Mooney M20J (see AAIB reference EW/C99/4/3 and our article Automatic Pilot = Automatic Crash?) I commented that the pilot was wearing a noise-suppressing headset and may thus have missed the audio stall warning that would have sounded before the aircraft stalled and begun its fatal spin into cloud. (For further comment on noise reducing headsets click here.)
The main message from the review of that accident was the need for pilots who operate aircraft fitted with autopilots to fully understand the operation and limitations and potential malfunctions of the autopilot fitted to their particular aircraft. The secondary message was to question the wisdom of using noise-suppressing headsets in GA aircraft. If the pilot is isolated from all sounds other then RT and intercom then he is isolated from a wealth of audio clues about the performance and operation of his aircraft. A slight change in the engine/propeller note can alert the pilot to the first stages of a potential problem. The sound of the airflow over the airframe also contains useful clues to anything abnormal. These “extraneous” noises are almost subliminal until they change – then you can pay attention to the fact that something has changed.
It is my opinion that noise-suppressing headsets in GA aircraft are little more than an expensive fashion accessory and do nothing to enhance safety. In fact, I believe they decrease safety by isolating the pilot from many safety-related audio clues like stall warnings and undercarriage warnings.
I thank SATCO Exeter for his valued input. I intend to extend the discussion about orbits in the visual circuit and their use at different airfields at a future date and hope to have further reaction from both sides of the fence to add to the discussion. I contend that a competent GA pilot with reasonable situational awareness who listens out before joining a visual circuit should be able to form an accurate mental picture of the traffic already in the circuit and so fit in without confliction or confusion. If he can’t he should not be there.
Text and Photographs © 2007 Gremline & Hill House
Publications, unless otherwise stated.
Text and Photographs © 2007 Gremline & Hill House Publications, unless otherwise stated.