Steve Ayres

Accident Analysis

With Steve Ayres


A notice to airmen!

Wading through Notam’s can be a pain, but as FLYER’s Safety Editor Steve Ayres suggests, there are some very good reasons why doing so might just be worth your while!

I am sure we have all been there, trawling through a long list of Notam for something that might, one day, spoil a beautiful day out. It can all seem a bit like looking for a needle-in-a-haystack on occasions, of course, but these incidents remind us why it can be really important to do so. And not just the night before. A last minute check before getting airborne or following a change of plan can prevent putting us and others at risk and help retain that valuable licence!

Accident 1

The pilot and a fellow member of the flying group had left their home base with the intention of flying to several different airfields. Their routing initially took them to Kirkbride Airfield where they swapped seats. 

They were intending to fly from Kirkbride to Prestwick Airport for the second leg of their route but, due to a lower than expected cloud base over high ground, they decided instead to route along the coast before stopping at Castle Kennedy. Both pilots were familiar with Castle Kennedy. 

“A tethered kite has a wingspan of 10m, and weighs 30kg… and is connected to a line with a breaking strain of 6,500kg”

Concern over weather and a possible maintenance issue at Kirkbride meant neither pilot consulted the Notam for the new route nor telephoned Castle Kennedy to gain PPR. Castle Kennedy Airfield is unlicensed and all operations are PPR except for aircraft based at the airfield. The owner of the airfield was, at the time of this incident, working with a company in developing technology for the generation of power from large tethered kites. As a result of this the airfield had an active Notam stating the runway would be closed during kite flying operations. 

A full-size kite has a wingspan of 10m, with a mass of 30kg. It can travel at speeds up to 100kt and is connected by a tether to a winch on the runway. The tether has a breaking strain of 6,500kg and this kite would present a significant hazard to any aircraft. The kite operates up to 1,100ft above the airfield.

During the flight, the pilot spoke with Scottish Information before transferring to the SafetyCom frequency (135.475 MHz) when the aircraft was approximately 10nm from Castle Kennedy. This allows pilots to broadcast their intentions when there is no frequency allocated to an airfield or landing site, and several broadcasts were made by the pilot before landing at the airfield.

As the pilot approached the runway he noticed there was something just short of the threshold but he was unable to make out what it was until he was in the flare. At this point he saw that the object was a cross which he thought was on a flag placed flat on the tarmac. He saw no further obstacles on the runway and considered that the safest course of action was to continue to land. After the aircraft was shut down, the pilot was approached by members of the kite company who pointed out that the runway was closed and a Notam was in effect.

The kite company was working at the airfield although they were not flying the full-size kite at the time. There were six members of staff around the airfield with some working close to the runway. A member of the staff was monitoring SafetyCom and was alerted to the imminent arrival of the aircraft. He was able to radio the staff working on the airfield so they could move away from the runway. 

It was estimated that it was only 3.5 minutes from the first transmission on SafetyCom until the aircraft landed. The kite staff commented that if they had been flying the full-size kite, this would have been insufficient time to lower the kite and move the equipment clear of the runway.

The pilot was surprised that Scottish Information did not inform him that the runway was closed at Castle Kennedy but it was not the responsibility of ATC to do so and the controllers were unlikely to have been aware of the runway state.

Accident 2

The pilot was carrying out a series of sightseeing flights, operating from a helicopter base at Manston disused airfield, Kent. The first flight departed to the south of Manston, along the coast at Sandwich Bay to Dover, before turning inland towards Canterbury and then back to Manston.

For the first part of the flight the pilot flew at altitudes of between 700ft and 1,000ft amsl, before climbing to 1,500ft amsl approaching Deal. As he was flying along the coast at around 700ft, he noticed a kite very close by and took avoiding action. He was not aware of any contact and continued the flight, landing back at Manston after approximately 25 minutes. 

The pilot then carried out a second flight in the same area. As he was flying along the coast north of Deal, towards Manston, at 1,500ft amsl he noticed a number of kites in the sky at levels which he estimated to be above 1,000ft amsl. 

Finally, there was a short (third) flight in a different direction, after which a person assisting with the loading and unloading of the helicopter noticed a scuff mark on the windscreen. He pointed it out to the pilot and the helicopter was shut down for investigation. Further damage was discovered to the right forward door screen, the main rotor pitch change links, one rotor blade and the vertical fin. The helicopter was grounded for a maintenance inspection.

The location where contact with the kite line most likely occurred was on the coast in Sandwich Bay. Online footage of activity at the same location shows a number of people flying kites with 700m line spools. Adapted power drills and winches are used to wind in the lines after flying.

Evidence from the nature of the damage to the helicopter and photographs taken at the probable kite flying location suggest that the kite string was coated with an abrasive substance. There is evidence that a number of different coastal locations in the UK are used for kite flying at heights above 60m but the activity is not being notified. 

Permissions for exceptions to Article 92 of the ANO can be obtained through the CAA. On receipt of an application, the location of the activity is checked with regards to the surrounding airspace and the activity’s impact on that airspace. Special conditions may be imposed for a permission to be granted, such as attaching streamers to the line to aid conspicuity, and a Notam will be issued.

Accident 3

A privately operated Fairchild Industries SA226-T Merlin III aircraft departed Bankstown aerodrome, New South Wales at 0720 for Mudgee Airport and then on to Dubbo City Regional Airport and Gunnedah airport, landing at the latter around 1550. 

At 1047 that morning a Notam was published closing Gunnedah airport on the following day between 0700 and 1500 for emergency runway works. On arrival at Gunnedah, as the aircraft was taxied to the parking bay, the pilot noticed a rough spot on the asphalt near the end of the runway. The aircraft was parked for the night. The next day around 1225, the pilot advised Brisbane Centre air traffic control that the aircraft was taxying at Gunnedah for departure. 

On receiving the taxi call, the controller checked for any current Notam and found one current for the airport, stating that it was closed due to works in progress. The controller attempted to inform the pilot but was unable to establish contact. 

“As the aircraft accelerated the pilot saw there were two holes excavated from the runway, which caught one gear leg”

About five minutes later, after taxying by the works in progress to the threshold and turning around, the pilot commenced the take-off run. He reported seeing patches on the pavement in the distance. As the aircraft accelerated along the runway, it was apparent there were two holes excavated from the runway pavement (3m wide by 5m long), about 30cm deep. The pilot tried to avoid the holes but was unable to clear them with the aircraft’s left main landing gear. 

The aircraft sustained damage to the left main landing gear assembly that resulted in it collapsing and the left propeller striking the ground. The aircraft veered off the runway and came to rest outside the flight strip.

Ayres’ Analysis

Don’t we all love that ‘night before’ scroll through the Notam on SkyDemon or some similar app. What seem like endless references to Covid restrictions that don’t affect most of us, unlit obstacles and suchlike. However, buried amongst all those irrelevancies there is an occasional nugget and woe betide any of us who miss it! 

I have always rather looked upon Notam as a necessary evil that rarely impacted my flying but increasingly there is something which affects what I want to do and requires a re-route or a complete replan. Those pesky kites, for example. I hadn’t realised until I read the first accident that they could be so big. I thought they were always flying bait for birds of prey or some such. Clearly not! 

Colliding with any object is worrying enough and all we can do is reduce the risk by being as aware as we can of areas where there is heightened aerial activity. As for airfields or runways that are closed, we are presented with a different category of risk and that risk is not just to ourselves. I was reminded of a close shave a colleague had when taking off on a misty morning and spotted some workmen on the side of the runway out of the corner of his eye. ATC had taken advantage of forecast poor weather and had Notam’d the airfield closed at short notice for maintenance. 

A salutary reminder that any ‘nighttime’ scroll is not necessarily sufficient and that a last minute check is essential, even at airfields which are very familiar to us or which may look ‘wide open’! We can only imagine the shock to the pilot of the Fairchild Merlin III as he was confronted by and tried to dodge the excavated sections of runway in Gunnedah! As with incidents of this type, a number of issues conspired to allow an accident to occur but ultimately a check of the Notam would, in both runway incidents, have flagged the danger.

So what about late changes to a plan or an unplanned diversion? Should we be thinking more along the lines of such occasions being an emergency and perhaps require external assistance? That is probably going too far in most circumstances but the incident with the PA-28 shows how badly things can go wrong. One reason given for not checking the Notam was a poor mobile phone signal prior to departing on the revised plan but this is invariably the case when an in-flight change is made. How confident can we then be that we are not going to fall foul of an unforeseen Notam? Certainly, that pre-departure check of Notam for the route and potential diversion airfields would be a good place to start!  

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