Safety Matters and Safety Briefs are based on the AAIB Bulletin and UK Airprox Board reports, with additional material from the US National Transportation Safety Board
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Superior? Not in the cockpit!
Aircraft Type: Piper Tomahawk Date & Time: 12 May 2018 at 1215 Commander’s Flying Experience: PPL, 199 hours, 57 on type Last 90 days: 15 hours Last 28 days: 8 hours
The pilot in the right seat of the Tomahawk was not a flying instructor. In the left seat was a senior work colleague who, while a student pilot, was not qualified to fly without supervision from an FI. Although he had received no instruction on the aircraft type it was he who made the takeoff from Blackpool and flew it to Caernarfon, with his PIC colleague monitoring his actions and making the R/T calls.
Following an overhead join for Runway 25 at Caernarfon, the unqualified pilot flew the circuit, but when established on final approach the PIC suggested that they were too high. The unqualified pilot acknowledged, but did not subsequently establish the correct approach path, so shortly before touchdown his colleague intervened, selected idle power and ‘followed through’ on the controls. He then took control and applied full power to go around, but did not move the flap lever from the landing position. Airfield CCTV imagery showed that the aircraft’s mainwheels made ground contact about one-third of the way along the runway, then it bounced, veered left of centreline, bounced twice again, and flew over the left edge of the runway in a nose-up, left wing-low attitude.
Realising that they were not gaining altitude and seeing a hangar ahead, the PIC turned the Tomahawk away from the hangar before the aircraft descended. CCTV imagery showed that it turned left as it departed the runway and climbed to about 20ft before adopting a wings-level, nose-up attitude, overflying a parallel taxiway and descending towards the ground, after which it was hidden from the camera’s view. After passing through the airfield fence it crossed a public road, hit another fence, turned over and stopped abruptly, pointing back towards the airfield.
The unqualified pilot saw fuel leaking from the left wing and it took him twenty seconds to undo his seat belt and escape. The PIC made engine and electric controls safe but was unable to undo his seatbelt, so his companion returned to assist him. Both had suffered minor injuries, but were quickly treated by paramedics from the local air ambulance unit.
In hindsight, the right-seat PIC realised that his decision to allow his companion to fly the aircraft was probably subconsciously influenced by the fact that he was a senior work colleague. He was aware that he was not a qualified pilot, so should not have handled the controls without being supervised by a flying instructor. Other safety lessons highlighted by the accident were that a go-around should be initiated if it looks unlikely that touchdown will be made in the first third of a runway, and the vital need to make an appropriate flap selection when going around. The PIC noted that, although he was in the habit of moving the flap lever during touch-and-go landings, his actions on this occasion were affected by being in an unexpected and stressful situation and thus, because full flap was still set, he subsequently lost control of the aircraft.
A clash of Ravens
Aircraft Type: (Both) Robinson R44 Raven Date & Time: 5 May 2018 1125 Commanders’ Flying Experience, 1: CPL, 913 hours, 226 on type Last 90 days: 54 hours Last 28 days: 21 hours Experience, 2: CPL, 6,846 hours, 1,705 on type Last 90 days: 62 hours Last 28 days: 13 hours
One Robinson R44 (’FL) had its rotors turning, prior to departing Cumbernauld for a trial lesson flight when another R44 (’ND) returned from a sightseeing flight. Because both helipads at the eastern end of the airport were occupied, the pilot of the arriving helicopter landed on a grass area behind ’FL and transmitted “secure on the ground complete”.
Parked on the northern of the two helipads was a Robinson R22 that had recently flown. Shortly after the sightseeing R44 ’ND had landed, the R22’s occupants walked in front of ’FL towards the helicopter operator’s buildings. The pilot of ’FL then obtained the latest airfield information and, a minute after the last transmission from the arriving R44 ’ND, radioed “Lifting from the eastern helipad to Alpha”. ’FL’S pilot’s view was restricted forwards and right of the parked R22 and by a stationary Cessna that was in front of him, facing away with its propeller turning. There was a second light aircraft parked left of the Cessna and he did not wish to disturb these with his helicopter’s downwash. He knew that, when he had boarded his helicopter, the area to the rear was clear, and he had no recollection of hearing any radio transmissions from the arriving R44, so was not aware of its position and not expecting another helicopter to be parked there. After lifting to the hover he decided to move rearwards and then taxi behind the parked R22. He did not turn his R44 to check that the area to his rear was clear before reversing because of the proximity of the R22, and because he did not want to turn his helicopter’s tail left towards the buildings, where some spectators had gathered. CCTV recordings showed that the R44 lifted before moving slowly rearwards and slightly right, with its skids about six feet above the
ground. The rotor blades of the just-arrived R44 were still turning slowly and one of them struck the engine housing of the hovering helicopter on the left side below its tailboom.
The departing R44’s pilot heard a bang and his helicopter pitched nose-up and right, so he made a forward cyclic control input to return towards the helipad and lowered the collective lever. He then realised that the helicopter was pitching nose-down so he moved the cyclic stick aft, the tail struck the ground and the R44 bounced forward off its skids towards the parked R22. Despite the R44’s pilot quickly making a left cyclic stick input its rotor blades struck the ground and it vibrated violently before landing heavily in a noseup attitude near the R22, with its tail resting on the ground. The helicopter operator’s staff helped the uninjured occupants to escape.
The pilot of ’ND had turned off his radio and removed his headset while the rotor blades slowed. After writing post-flight notes he looked up and saw the departing helicopter moving towards him. He tried to turn his radio on and replace his headset so that he could warn the other pilot, but before he could do so the blade strike occurred. His three passengers were uninjured and when the rotor blades stopped turning they all disembarked normally.
CCTV recordings of the collision showed that the departing R44 pitched rapidly to approximately 45º nosedown, but initially maintained its height above the ground while moving away from the other and towards the helipad. As it approached the pad it descended and the nose pitched up, its tail struck the grass and the rear of both skids hit the concrete, causing it to bounce about two feet from the ground into a nose-down attitude, while the tail turned anti-clockwise towards the parked R22. It then struck the ground heavily, orientated at 90º to the pad, with the left skid hitting first and the helicopter then rolling onto its right skid and pitching nose-up until its tail struck the ground. The R44 now bounced a second time, its tail turned quickly clockwise and it rolled left until the main rotor blades struck the concrete pad and it finally hit the ground between the two landing pads with its tail on the grass close to the R22. Its rotor blades stopped turning 33 seconds later.
Cumbernauld Airport’s operator had agreed that the helicopter operator would provide its own Rescue & FireFighting Service (RFFS) for all associated helicopter operations and the operator’s own RFFS vehicle was available, parked outside the hangar a few metres from the accident site. But the only trained RFFS personnel available were the pilots from the R22 and the just-arrived R44. Another employee who was the first to reach the accident site saw no evidence of leaking fuel when he helped the passengers to escape, and when the R22’s pilot reached the scene he concluded that there was no fire risk, so the RFFS vehicle was not deployed. The airport’s A/G radio operator, who had activated the crash alarm, was also trained for RFFS duties. Not seeing the helicopter operator’s RFFS vehicle deploy he passed his radio task to somebody else and drove the airport’s own RFFS vehicle to the accident site. He arrived within two minutes of the accident, and found the R44’s occupants uninjured and that its operator did not believe there was a fire risk, so local emergency services were not alerted.
The helicopter’s operator conducted an internal investigation which concluded that the accident could have been avoided if the pilot of the departing R44 had turned its tail and made a ‘lookout turn’ to visually check the area behind, which it considers to be a standard procedure. The R44’s pilot said that he had felt constrained from moving the tail of his helicopter by the presence of spectators, but CCTV recordings showed nobody on the roadway or grass area immediately to the left of the R44, and its operator believes that its tail could have been moved left, leaving a five-metre safety margin from any people or obstructions. As a result of the accident, the helicopter operator has taken the following safety actions:
The northern helipad has been extended eastwards by 12m, so a parked helicopter is further from the apron, leaving space for other helicopters to move between a parked helicopter and the apron
The prepared grass area east of the helipads has been extended, to ensure that helicopters parked there can remain well clear of the pads
A mirror has been placed at the corner of the hangar, to
assist pilots using either helipad see any activity to their rear
The helicopter operator no longer permits helicopters to reverse from the helipads
The helicopter operator’s safety team is due to review the procedure for turning off avionics while an R44 is being shut down
Changes have been made to RFFS procedures to require two appropriately-trained employees to be available on the ground at all times of helicopter activity, and that firefighting equipped can readily be accessed by them.
The AAIB commented: ‘The collision between the two helicopters occurred because the pilot (of ’FL) was not aware of (’ND’S) position. However, the damage to (the former) did not appear to immediately affect the operation of its engine or flying controls. [Its pilot] stated that he recalled his helicopter pitching nose-up and he made a forward cyclic input in response, but CCTV showed that after hitting [’ND] his helicopter pitched nosedown. An excessive nose-down attitude ensued, close to the ground, before recovery action appears to have been initiated and the nose began to pitch up. However, the helicopter was now descending towards the helipad and, as the nose pitched up, the tail struck the ground and initiated the impact sequence. It is likely that the pilot was startled by the unexpected collision with the other helicopter. The “startle effect” is likely to have impaired his ability to comprehend the situation and also his psychomotor skills, leading to his loss of control.’
Airproxes… and how to avoid them
the Board. ‘On the one hand the PA-28 pilot was required to conform with the traffic already in the visual circuit, one of which was the Cherokee Six, but on the other hand the Cherokee Six’s pilot was required to give way to traffic ‘in the final stages of an approach to land’, which included the PA-28 heading straight-in.’
The Board agreed that, routinely, those joining straightin should only do so if they can integrate effectively with those already in the visual circuit, and cautions pilots about assuming priority simply because they have called a straight-in approach. ‘Equally, if in the circuit and another pilot does join straight-in then it may be that they’ve done so for good reason, so discretion may be the better part of valour−give them room and, if necessary, go around early and talk about it later over tea!’
During its September meeting the Board assessed 31 incidents: 18 aircraft-to-aircraft, with six having a definite risk of collision (two Category A, four Category B). ‘The number of aircraft-toaircraft reports so far this year sits just above the expected five-year cumulative average at 146 but, at 112 incidents, drone/suas reports have now already reached 2017’s levels with just over a quarter of the year still to go,’ the Board notes. ‘This month’s incidents were mostly Ga-biased, reflecting the fact that we are now processing Airprox from the summer months when GA flying increases. The two dominant themes were sub-optimal planning and integration with other aircraft (nine), and seven occurrences of late- or non-sightings.
‘For the former, poor visual circuit planning and execution predominated, with pilots either not thinking ahead, not properly planning their integration, or not following circuit procedures. For the latter, an increase in late- and non-sightings is typical in the summer months as airspace becomes busier and emphasises the need for pilots to prioritise a robust and effective lookout over in-cockpit tasks (the 80:20 rule−with eighty per cent of the time looking out of the cockpit).
‘There were three incidents where inaction resulted in aircraft needlessly coming close to each other. One was a failure to give way, while in the other two, pilots assumed the other had seen them and would give way, which, given the eye’s performance limitations, is an inappropriate assumption. ATS non-availability or sub-optimal application also featured in three other incidents, with controller workload being cited as contributory in two.’
The UKAB’S latest 2018 performance graphs revealing the weakest and strongest safety barriers to Airprox cite 69 incidents from which, it says, ‘some interesting perspectives can be drawn’:
See-and-avoid was either ineffective or only partially effective in 54% of incidents
Collision warning systems were either absent or ineffective (mostly due to incompatibility) in 66% of incidents
Pilot situational awareness and subsequent action regarding the other aircraft was either ineffective or only partially effective in 75% of incidents
When present and used, ATC situational awareness and action was effective in about 62% of involved incidents: it was not present in 28%, and not used (mostly due to an inappropriate service being requested) in 30%.
‘The stand-out item is the use, or not, of collision warning systems,’ the Board concludes. ‘Increasingly affordable systems are now available, and for about the price of a couple of tanks of fuel some hugely valuable situational awareness can be gained from them about other aircraft in the area. While they’re not infallible and can only function if suitably compatible systems (i.e. secondary surveillance radar) are detected, they might just make the difference when all other barriers are not performing well.’ Airprox reports can be read in full at:
The result of an unqualified student pilot flying and a full flap go-around
The departing R44 landed heavily nose up with its tail on the ground
PA-28 and Cherokee Six conflict diagram – who had the priority?