CAA

How did that happen?

David Learmount , , , , , , , , , ,
How did that happen? A Boeing Stearman lands on a Cessna 182.

A Cessna 182 was nearing the end of its landing roll on runway 22 at Dunkeswell aerodrome, Devon, UK, when a Boeing Stearman landed on top of it.

Remarkably, both pilots survived, but the Cessna pilot was badly wounded when propeller blades cut through the top of his cockpit.

The Air Accident Investigation Branch report describes what the Cessna pilot experienced: “With around 100 m to go to the [runway] intersection [where he intended to turn off to the right], the pilot reported that he heard and felt what seemed like an ‘explosion’ and then became aware of propeller blades rotating in front of his face. He recalled that the cockpit was filled with debris from the shattered windshield, shards of metal and splintered wood.”

It was a cloudy day but the visibility was pretty good below the cloud-base, which was 1,200ft above ground level, with a few patches at 600ft to 800ft. The AAIB says Dunkeswell witnesses described the weather as “workable”.

The pilots of both aircraft say they made calls on the Dunkeswell Radio frequency, but only the Cessna pilot received a reply.

Both pilots were alone in their aircraft, and both of them were experienced aviators.

Neither was aware of the other aircraft’s presence in or near the Dunkeswell circuit, and at the point of collision neither had seen the other.

If I were to stop the story here, even experienced general aviation pilots would wonder how this situation could possibly have developed. The answer, as usual, is that lots of factors combined; but even after reading the AAIB’s report, some questions remain unanswered.

The assembled contributory factors – in no particular order – are these: Dunkeswell Radio maintained an imperfect listening watch for its air-ground communication service (not ATC as such), the duty officer having multiple other duties while on watch; the Cessna pilot (G-OMAG) intercepted final approach from the “dead side” without clearing the non-standard arrival; the Stearman pilot (N68427), based at Dunkeswell, states he made several calls to Dunkeswell Radio when returning to the circuit, but received no response; neither pilot heard any calls from the other, both believing they were alone in the circuit; forward visibility from the Stearman’s cockpit is limited, especially directly ahead and below the nose. Finally, the AAIB found that the airport operator was not aware that the main AIP (aviation information publication) entry for Dunkeswell did not contain reference to the requirement for inbound traffic to join the circuit via either the downwind or base legs of the active runway. Accordingly, commercial AIP providers did not do so either.

The sequence on the day (20 August 2021) goes something like this: the Cessna, having obtained prior permission to arrive at Dunkeswell, took off from Bodmin – about half an hour to the west – at 13:00. The Stearman had taken off from Dunkeswell at 13:05 to carry out some flying in the local area to the north, and returned later intending a couple of circuits.

At 13:26 the Cessna passed Exeter to its north, and at the same time the Stearman joined Dunkswell’s left hand circuit for runway 22 from the east, and carried out a touch-and-go at 13:29. The Stearman pilot said he made a radio call indicating his intentions but could not recall getting an acknowledgement. Following his touch-and-go, N68427 flew a left hand circuit (see illustration below), intending to land from a curved base leg into a short final approach, because the wing-down attitude provides better sight of the runway for a Stearman pilot.

At about 13:27 the Cessna pilot called Exeter and said he was continuing with Dunkeswell Radio, then called the latter and was informed runway 22 was active with a QFE of 986hPa.

The AAIB report says that when the Stearman entered the 22 left hand circuit from the touch-and-go, the Cessna was about a mile to the west of the airfield, the dead-side of the circuit. The Cessna pilot decided to turn north (see illustration above), then carry out a right hand loop onto the base leg, continuing the turn onto final approach from the dead side. At that point, says the Cessna pilot, he called “Golf alpha golf final 22”. There was no acknowledgement, and the pilot told the AAIB he thought his aircraft was alone in the circuit.

CCTV images of the two aircraft show the two aircraft on final approach, the Stearman slightly higher, initially curving in from the left of the runway extended centreline, the Cessna on the centreline. As they converged, the Stearman remained higher than the Cessna and slightly ahead of it, the latter overhauling the biplane because of its faster approach airspeed. When the Cessna touched down just beyond the displaced runway threshold, the Stearman was above and close behind it, with the Cessna in the pilot’s blind spot below the biplane’s nose.

As the Cessna slowed toward its intended turn-off, the Stearman “touched down” on top of it. The AAIB report provides the Stearman pilot’s perception of what was happening: “The pilot reported that the landing ‘didn’t feel right’ and that the aircraft was not responding to control inputs. He applied power to correct what he felt was a drift to the left, then reduced power to idle. The aircraft continued to swing further to the left, off the runway and onto the grass.” (see headline picture).

The Cessna pilot could not open his cockpit door, but the Stearman pilot managed to do it and helped him out. The airport fire and rescue service attended rapidly and doused the Cessna with foam because fuel was leaking from the left wing tank.

Because the airfield only provided an air-ground communication service, not ATC as such, communications are not logged, but the pilots and some airport witnesses report calls being made in this case. The mystery is: why didn’t either pilot hear the other’s calls?

The UK Civil Aviation Authority’s Skyway Code provides plenty of apposite advice for this serious incident. One piece is this: “If you believe the circuit is clear but are not sure, there is no harm in asking over the radio whether there is any other traffic – it is not unknown for pilots to stop making position calls if they believe they are alone in the circuit.” Another is to stick rigidly to circuit procedure, which would include not joining from the dead side.

UK aviation: caught in the crossfire

David Learmount , , , , , , , , , , , , , , , , , , , ,

With the destabilizing effects on global aviation of huge fuel price inflation and unprecedented Russian military aggression in Europe, worsened by post-pandemic staffing shortages, it’s amazing that international commercial air transport works at all right now.

International cooperation has never been more crucial. Yet in the UK, an example of how NOT to do aviation – especially right now – has just been highlighted.

UK-based eVTOL developer Vertical Aerospace will be certificated by the UK CAA according to EU rules despite having separated from EASA

The reason international aviation is still working despite global instability is because the world wants it to, and has set up robust systems to enable it. Like commercial shipping, commercial aviation is naturally a global industry.

That’s why both those industries have specific United Nations agencies devoted to overseeing globally agreed standards and operating practices (SARPs). These agencies are the International Maritime Organization and the International Civil Aviation Organization. Total regulatory unity doesn’t prevail worldwide, but a high degree of harmonization does.

The world’s two most influential national/regional aviation authorities responsible for turning ICAO SARPS into national law are the European Union Aviation Safety Organisation (EASA) and the US Federal Aviation Administration (FAA). These two have worked together for decades to improve the harmonization of their regulations, making them identical where possible. They still meet regularly. Most of the world’s national aviation authorities (NAAs) more or less copy the regulations of one or the other into their own NAA rules.

All the EU states have always had their own NAAs – and still do. But since the 1980s they have worked together on harmonizing their aviation regulations to make Europe’s aviation industry work better.

In the early 2000s, EASA was born out of its predecessor the European Joint Aviation Authorities, to unify Europe’s interpretation of all those ICAO SARPs.

Back in the early 1980s, believe it or not, Boeing had to build almost as many variants of its 737 series as there were countries in Europe, because some nations insisted on safety systems than the FAA did not require, and some of these specifications were unique to each country. For example, one of the UK’s additional requirements – then – was for a 737 stick-pusher.

Today the UK Civil Aviation Authority (CAA) is faced with the consequences of returning to the bad old days because of the UK’s departure from the European Union. Although Theresa May, the UK prime minister preceding Boris Johnson’s election, had instructed the CAA to remain an associate member of EASA following “Brexit”, when Johnson came in his government insisted on ideological purity, thus no CAA association with Europe’s multinational agency.

Meanwhile, right now the CAA has to prepare its reaction to the imminent arrival on the world stage of a new form of commercial air transport: eVTOL (electric vertical take-off and landing), also known as Urban Air Mobility. Expected to take the air taxi world by storm and make it sustainable, the UK plans to be involved in all aspects of this new industry, including manufacturing.

At a time like this, when the world has agreed to harmonize rules associated with another massive new aviation development – drone operation – it does not make sense for any nation to declare unilateral independence from the world rule-making processes.

The CAA, fully aware of its dilemma, has released a statement pledging that it will follow exactly the EASA rules on certification for eVTOL.  Of course, it has to duplicate the regulation in UK law, and any UK eVTOL products or services will be subject to scrutiny by EASA to ensure that it does just that. Hence the UK’s promising eVTOL manufacturer Vertical Aerospace is having to undergo identical parallel certification by two agencies: the CAA and EASA. You couldn’t make it up, could you?

Meanwhile the bureaucratic burden placed on the UK agency is evident from this script heading pages on the CAA’s website: “UK-EU Transition, and UK Civil Aviation Regulations: To access current UK civil aviation regulations, including AMC and GM, CAA regulatory documents, please use this link to UK regulation. Please note, if you use information and guidance under the Headings below, the references to EU regulations or EU websites in our guidance will not be an accurate description of your obligations under UK law. These pages are undergoing reviews and updates.”

Shoreham and the future of air shows

David Learmount , , , , , , , , , , ,

No person or organisation associated with the 2015 Shoreham flying display accident escaped criticism – implied or actual – in the Air Accident Investigation Branch’s final report.

When the aircraft that later crashed, the Hawker Hunter T7, took off from its North Weald, Essex base heading for Shoreham to fly the display, it had several time-expired or unserviceable components in it. In retrospect the AAIB report says it was not in compliance with its permit to fly, yet none of these faulty components caused the accident.

The Flying Display Director hired to manage show safety was fully qualified in terms of knowledge, experience and expertise to oversee all aspects of the flying display, but the report implies there were some things – like the exact display routine the Hunter was to fly – he should have risk-assessed manoeuvre by manoeuvre. Yet even if he had, the crash might still have happened.

The Hunter’s pilot was fully qualified in terms of experience, training, flying recency and medical fitness to carry out the display he had planned, but on the day he got one of the aerobatic manoeuvres badly wrong, making mistakes that are difficult to understand in somebody so experienced.

The mistakes meant that he himself was seriously injured when thrown clear of the aircraft on impact with the A27 highway next to the airfield, but 11 people on the road were killed.

By flying a similar Hunter through the same manoeuvres, the AAIB has determined that the pilot could not have pulled the aircraft out of his “bent loop” without hitting the ground once he had passed the apex too low and failed, at that point, to carry out an “escape manoeuvre” by rolling the aircraft upright.

If he had used his ejection seat during the high speed descent from the loop it would not have saved him, and the pilotless aircraft would have continued to impact with the ground, possibly in much the same place. The only way the pilot could have prevented killing the people on the A27, says the report, was to crash the aircraft into nearby fields, but during the last second or so he probably still hoped he could avoid harm to road-users by pulling up in time.

Why was he too low at the loop’s apex?

He should have entered the loop from a 500ft base, but he started at about 185ft. The height of the top of a loop compared with the entry height is a product of speed and engine power at entry. The aircraft should have entered at a minimum 350kt with full power selected, but the Hunter entered at 310kt with less than full power until well into the pull-up. The pilot should have aimed for a 4,000ft apex with 150kt indicated airspeed over the top, but in fact it got to less than 3,000ft with 105kt.

Unless the pilot recognised the lack of energy at that point and carried out the rolling escape manoeuvre, he and the aircraft were doomed.

Why a pilot with so much experience of teaching, let alone flying, aerobatic manoeuvres failed to heed these indicators that the loop was going wrong may never be known, because trauma has obliterated the details of the fatal flight from the pilot’s memory, according to the report.

Air shows involve risk. A study by the AAIB has recently quantified that risk, and my blog a year ago describes the findings in detail.

The final Shoreham report confirms the impressions given by the earlier AAIB bulletins on the subject. Because no-one in an on-site air display audience in UK has been killed since the early 1950s, such success appears to have led to complacency.

Not rampant complacency, but a relaxed belief that all the people involved are experts who know what they are doing, so they don’t need to be given the third degree before a show.

The sign that not all was well was the number of serious air display accidents, mostly fatal, that occurred just outside the area controlled by the display organisers – just like the Shoreham Hunter crash.

The AAIB found that 65% of all air show accidents came into that category, but almost always the only person harmed was the pilot. So nobody, including the CAA, raised the alarm, until now.

Meanwhile aerodromes used for decades as air show venues have suffered encroachment at their boundaries by expanding residential and industrial development. This affects the profiles aircraft are allowed to fly during a display, and flight display directors are bound to take this into account.

No longer are display lines, and entry and exit profiles dependent purely on where the display audience “crowd line” is, they have to take into account what each aircraft would have to do in the event of a technical or operational mishap during the display to avoid crashing into a nearby populated zone.

These are considerations that will affect air shows in the future. If a flying display stops being exciting, it might as well give up. Or go somewhere else more rural.

Coastal air displays will survive, because the escape route for aircraft in trouble is obvious.

The best example of the conundrum air show organisers face is what has happened to the traditional Red Arrows display at the biennial Farnborough International Air Show. When the Reds reviewed their Farnborough routine in detail following the tightened guidelines published in the early Shoreham bulletins, they found they had to curtail their display considerably.

In a statement following the release of the Shoreham final report, the CAA says: “We are fully committed to ensuring that all air shows take place safely, for the six million people who attend them each year in the UK and for the communities in which they take place.”

Let’s hope the CAA means what it says.