Safety Mat­ters

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

Pilot - - CONTENTS -

Flap mis­ad­ven­ture, un­der­car­riage mishaps and lat­est Air­prox re­ports

Fa­tal full-flap take­off

Air­craft Type: Cessna F150M Date & Time: 17 Oc­to­ber 2016 at 1021 Com­man­der’s Fly­ing Ex­pe­ri­ence: PPL(A), 363 hours, 9 on type Last 90 days: 7 hours Last 28 days: 2 hours The pi­lot had started fly­ing from Bourn Air­field six months be­fore the ac­ci­dent. At that time he had not been fa­mil­iar with the Cess­nas which were avail­able at the lo­cal fly­ing club, so he was checked out by an in­struc­tor in both a Cessna 150 and C152 and com­pleted four hours of dual train­ing, a pro­fi­ciency check, twenty min­utes of solo flight, and sev­eral sub­se­quent flights ac­com­pa­nied by the same in­struc­tor. On the day of the ac­ci­dent he planned to take his fa­ther-in-law for a flight to En­stone and booked the C150, whose fuel tanks he was seen to top off to just below their filler caps. Af­ter pre-flight­ing he tax­ied to the thresh­old of Rwy 18, fol­lowed by a C152 with an in­struc­tor and stu­dent aboard, then ra­dioed that that he was ‘rolling’. The C152’s oc­cu­pants saw the air­craft get air­borne but not ap­par­ently climb­ing, and re­alised that its flaps were fully de­ployed. The in­struc­tor tried to ra­dio a warn­ing to the pi­lot, but it was too late to be ef­fec­tive and there was no re­sponse. The C150 con­tin­ued to­wards a line of trees be­yond the end of the run­way, its nose pitched up, its left wing dropped and it en­tered an in­cip­i­ent spin, de­scend­ing quickly to the ground. Peo­ple from the fly­ing club and a nearby in­dus­trial site ran to the scene and helped the badly in­jured pas­sen­ger from the air­craft. The un­con­scious pi­lot was re­leased but res­cuers were not able to sus­tain his breath­ing. Emer­gency ser­vices ar­rived and a para­medic con­tin­ued to at­tempt to re­sus­ci­tate him, but with­out suc­cess.

The air­craft had come to rest in a steep nose-down at­ti­tude against trees. Marks close to their bases in­di­cated that it had struck the ground in a near ver­ti­cal at­ti­tude The im­pact was con­sis­tent with it hav­ing been in a spin to the left, with the ve­loc­ity vector pri­mar­ily in the down­wards, as op­posed to hor­i­zon­tal, di­rec­tion. The flaps were at their max­i­mum 40° de­flec­tion, and ab­sence of abra­sion marks on them or ad­ja­cent fuse­lage struc­ture in­di­cated that they had been in this po­si­tion prior to im­pact.

Un­til the ac­ci­dent flight the pi­lot had not flown a C150 with­out an in­struc­tor. Notes the AAIB: ‘Although [the C150] has many sim­i­lar­i­ties with the C152, there are some sig­nif­i­cant dif­fer­ences. Flap se­lec­tion and in­di­ca­tion are dif­fer­ent and the C152 has a greater avail­able pay­load.’ ( Weight-and-bal­ance cal­cu­la­tions made by the AAIB sug­gested that, with full fuel, two oc­cu­pants and 48 lb of bag­gage aboard, the C150 had been about 88 lb

above its max­i­mum au­tho­rised weight — Ed.) ‘The C150’s flap switch does not give a vis­ual in­di­ca­tion of the se­lected po­si­tion [though] fi­nal pro­duc­tion mod­els (this was an ear­lier air­craft) were fit­ted with a re­designed flap se­lec­tor with de­tents for the flap po­si­tion and a po­si­tion indi­ca­tor be­side the switch. The C152 flap se­lec­tion and indi­ca­tor is sim­i­lar, but the max­i­mum flap travel was re­duced from 40° to 30°.’

The air­craft’s Flight Man­ual in­cluded the fol­low­ing note: ‘Flap de­flec­tions greater than 10° are not rec­om­mended at any time for take­off.’ The in­struc­tor who had pre­vi­ously flown with the pi­lot stated that he thought it was likely that 10° flap would have been se­lected for take­off on the grass run­way sur­face as this was the club pol­icy and had been prac­tised dur­ing the pi­lot’s train­ing and fa­mil­iari­sa­tion flights. The check­list in the air­craft’s Flight Man­ual does not in­clude de­ploy­ing the flaps prior to a walkround in­spec­tion, but the pi­lot’s com­mer­cially avail­able check­list, like many oth­ers com­monly in use, did in­clude this ac­tion.

His in­struc­tor com­mented that the pi­lot’s use of the check­list was me­thod­i­cal and dur­ing train­ing they had had dis­cus­sions about the lay­out of this check­list, specif­i­cally that se­lec­tion of the master switch ON as part of the ‘In­ter­nal’ checks be­fore car­ry­ing out a long se­quence of ac­tions in­clud­ing re­tract­ing the flaps, might drain the air­craft’s bat­tery. The in­struc­tor said that the pi­lot had made some marks on his check­list to high­light this prob­lem. The check­list, re­cov­ered from the air­craft af­ter the ac­ci­dent, was open at the ‘Vi­tal Ac­tions’ page which in­cluded se­lect­ing Flaps 10° for take­off in ac­cor­dance with club pol­icy.

The AAIB re­port con­cludes: ‘The take­off was at­tempted with 40° flap, prob­a­bly un­in­ten­tion­ally, which led to an in­abil­ity to climb be­cause of the ad­di­tional drag. This was ex­ac­er­bated by the air­craft be­ing above its max­i­mum al­low­able weight. A gen­tle turn to the left to­wards open ground or an early de­ci­sion to abort the take­off and land ahead could have pre­vented the ac­ci­dent. It is likely that the pi­lot did not re­alise why the air­craft was not climb­ing. A late at­tempt to re­tract the flaps would not have been an ef­fec­tive mit­i­ga­tion, as it takes ap­prox­i­mately six sec­onds to fully re­tract the flaps and flap re­trac­tion would have caused a tem­po­rary loss of climb per­for­mance.

‘The flaps were seen to be fully de­ployed dur­ing the pi­lot’s pre-flight in­spec­tion and it was not de­ter­mined whether they were ever re­tracted sub­se­quently. The flap switch on this air­craft did not give any vis­ual cue of the flap po­si­tion, un­like the oth­er­wise sim­i­lar C152. Thus, the flaps may have re­mained de­ployed un­til take­off, or may have been re-de­ployed prior to take­off. In the lat­ter case the pi­lot would not have in­tended to de­ploy full flap, so its se­lec­tion would have been ac­ci­den­tal. To de­ploy the flaps to 40° re­quires a sus­tained ac­tion on the switch for about nine sec­onds, so it is un­likely that this would be achieved by an ac­ci­den­tal in­put, although it re­mains a pos­si­bil­ity.

‘If the pi­lot had com­pleted the ac­tions as de­tailed on his amended check­list, that is, the master switch re­main­ing OFF un­til im­me­di­ately be­fore en­gine start, then with no elec­tri­cal power the flaps would not have re­tracted at ‘Item 8 Flaps — Up and check sym­met­ri­cal op­er­a­tion.’ In this cir­cum­stance it is pos­si­ble that the po­si­tion of the flaps and their fail­ure to move when se­lected UP es­caped his no­tice.

‘The next op­por­tu­nity to check the flaps through use of the check­list was as part of the ‘Vi­tal Ac­tions’, where the flaps are set at 10° for take­off. How­ever, there are eleven items in this sec­tion of the check­list and a fur­ther five items for the ‘Take Off’ check­list. It would be easy to over­look one ac­tion, and there is the po­ten­tial for ad­di­tional dis­trac­tion with a pas­sen­ger on board. It is also of note that the ma­jor­ity of the pi­lot’s pre­vi­ous fly­ing had been in tour­ing mo­tor glider air­craft which were not equipped with flaps.

‘Sig­nif­i­cant dif­fer­ences ex­ist in the de­sign and op­er­a­tion of flaps be­tween C150 and C152 air­craft. The C150 has the fa­cil­ity to de­ploy 40° flap, but in­ap­pro­pri­ate use of this flap causes per­for­mance penal­ties and han­dling prob­lems which can lead to ac­ci­dents for un­wary pi­lots. The spring-loaded switch, as fit­ted to (the ac­ci­dent air­craft) and most C150s, does not give the pi­lot a vis­ual cue of the se­lected flap po­si­tion, un­like the C152’s. It is there­fore im­por­tant that this dif­fer­ence is em­pha­sised dur­ing pi­lot train­ing.’ How­ever, the AAIB re­port notes that: ‘A me­chan­i­cal flap po­si­tion indi­ca­tor was pro­vided in the left for­ward door post/ wind­screen pil­lar; in ad­di­tion the flap ex­ten­sion could be seen from within the cock­pit. The indi­ca­tor con­sisted of a spring-loaded pointer run­ning in a slot in the pil­lar, with cal­i­bra­tion marks from 0°-40° de­grees on the sur­round­ing trim.’

The re­port con­tin­ues: ‘There have been two re­cent ac­ci­dents in the UK whereby the in­ad­ver­tent use of 40° flap on the Cessna 150 has been a causal fac­tor. It is con­sid­ered that a greater fo­cus dur­ing train­ing/type fa­mil­iari­sa­tion on flap se­lec­tion and in­di­ca­tion, and the ef­fect of full flap con­fig­u­ra­tion on air­craft per­for­mance and han­dling char­ac­ter­is­tics,

could pre­vent fur­ther ac­ci­dents. The fol­low­ing Safety Rec­om­men­da­tion is there­fore made: That the Civil Avi­a­tion Au­thor­ity pro­mul­gates to fly­ing in­struc­tors the need for spe­cific train­ing to high­light the dif­fer­ences be­tween the C150 and C152 flap switch de­signs. Train­ing should also in­clude the ef­fect on air­craft per­for­mance and han­dling of Flap 40°.’ A Gen­eral Avi­a­tion Safety Com­mit­tee study of UK stall/spin ac­ci­dents noted that there have been eleven such ac­ci­dents on Cessna 150s but only one on a C152, with sixty per cent more hours flown by the lat­ter type. It rec­om­mended that ‘The Cessna 150 and Cessna 152 should not be treated as the same type, and in par­tic­u­lar pi­lots trans­fer­ring from the Cessna 152 to the Cessna 150 should un­der­take for­mal Fa­mil­iari­sa­tion Train­ing.’

Left-hand, right-hand con­fu­sion

Air­craft Type: Maule Star Rocket Date & Time: 28 April 2017 at 1110 Com­man­der’s Fly­ing Ex­pe­ri­ence: PPL, 183 hours, 20 on type Last 90 days: 7 hours Last 28 days: 7 hours The air­craft had flown from Good­wood to Ea­gle­scott, whose air­field man­ager had taken a tele­phone call from the pi­lot when he re­quested PPR and ad­vised him to ar­rive in the over­head at 2,000ft QFE for a stan­dard over­head join for a left-hand cir­cuit for Rwy 07. The pi­lot made the re­quired ra­dio call, and as he ap­proached the over­head re­ported that he was let­ting down on the dead-side for a right-hand cir­cuit on 07. The air­field man­ager said that as the ra­dio calls were con­fi­dent, and there was no other traf­fic, he did not cor­rect the pi­lot, who then re­ported ‘Down­wind Rwy 07’ at a po­si­tion that the man­ager con­sid­ered to be closer to the air­field than nor­mal.

He con­tin­ued to watch the Maule and no­ticed that af­ter it had made a slight de­scent on the base leg it then flew a right or­bit, so he made a ra­dio call sug­gest­ing that the pi­lot go-around and com­plete a stan­dard left-hand cir­cuit. The pi­lot did not re­spond and con­tin­ued or­bit­ing. The man­ager then made a sec­ond call when the air­craft was point­ing to­wards the air­field stat­ing “Go-around, go-around, climb straight ahead, and per­form a stan­dard left-hand cir­cuit.” The air­craft then seemed to make a 45˚ join onto fi­nal from base leg and when on fi­nal ap­proach ap­peared to start a go-around. Dur­ing this ma­noeu­vre the air­craft de­scended but the pi­lot did not ad­e­quately mon­i­tor air­speed and it stalled. With in­suf­fi­cient height to fully re­cover, it crashed in a field short of the run­way. Pi­lot and pas­sen­ger were un­in­jured, but the air­craft was ex­ten­sively dam­aged.

The AAIB com­ments: ‘The pi­lot had cor­rectly writ­ten in his flight plan that he should fly a left-hand cir­cuit. He used a tablet de­vice to nav­i­gate and, en route, checked the air­field in­for­ma­tion recorded on the de­vice, which stated that pi­lots should fly a right-hand cir­cuit. On re-check­ing the air­field in­for­ma­tion on the de­vice af­ter the ac­ci­dent, the pi­lot re­alised that this re­ferred to glid­ers and that fixed-wing pow­ered air­craft should fly a left-hand cir­cuit. With a pas­sen­ger sit­ting in the front right seat, it would have been dif­fi­cult for the pi­lot in the left seat to re­main in sight of the run­way when fly­ing a right-hand cir­cuit close to the air­field.’

Air­prox re­ports

Air­man­ship a key is­sue The UK Air­prox Board re­viewed seven­teen air­craft-to-air­craft and four­teen air­craft-to-drone in­ci­dents at its July meet­ing. Five of the air­craft-toair­craft in­ci­dents were as­sessed as hav­ing a def­i­nite risk of col­li­sion (Cat­e­gory B), as were seven of the drone in­ci­dents.

‘The main theme this month was air­man­ship,’ says the Board. ‘[There were] five cases of sub-op­ti­mal in­te­gra­tion with other air­craft ei­ther in the vis­ual cir­cuit or radar pat­tern; three in­ci­dents re­sult­ing from pi­lots not act­ing on traf­fic in­for­ma­tion or as­sum­ing that the other pi­lot had seen them; and three events in­volv­ing pi­lots fly­ing in airspace that they were not en­ti­tled to op­er­ate within or not fully un­der­stand­ing the im­pli­ca­tions of the airspace they were us­ing.

‘As ever, the in­te­gra­tion in­ci­dents were largely avoid­able if pi­lots had thought ahead and al­lowed for the fact that the other airspace users might have been there, and two of these in­ci­dents hap­pened when the pi­lots knew about the other air­craft, had it vis­ual, but still got them­selves into a sit­u­a­tion where they ran out of ideas and op­tions be­cause they did not make early enough de­ci­sions.’

The Board’s Air­prox of the Month in­volved a Piper PA-28 and Cessna 152 in the Big­gin Hill cir­cuit. The Piper’s pi­lot joined the cir­cuit down­wind and was aware that he was catch­ing up on the C152 ahead. ‘He tried to slow down, as­sessed that he prob­a­bly wouldn’t get his ap­proach in, but thought he would con­tinue, watch the C152 land, and go-around over the top of it,’ says the Board. ‘He turned base and fi­nal, but then found him­self di­rectly in con­flict with the C152 and be­came un­cer­tain of what he should do to re­solve the sit­u­a­tion. Run­ning out of ideas, he ended up fly­ing very close to the C152 be­fore even­tu­ally go­ing around. Shaken by the in­ci­dent, the PA-28 pi­lot re­alised he should have done some­thing about the sit­u­a­tion much ear­lier, such as or­bit­ing down­wind, go­ing around early, or even leav­ing the cir­cuit en­tirely. How­ever, hav­ing got him­self into a sit­u­a­tion where he was now so close to the other air­craft, he didn’t know what to do for the best.

‘Although it’s easy to be wise af­ter the event, the les­son is that an early de­ci­sion is the key to re­solv­ing any sit­u­a­tion where your plan doesn’t seem to be work­ing out. Although it’s some­times dif­fi­cult to swal­low your pride, as the old adage goes “If there’s any doubt, then there’s no doubt” — make a new plan that re­moves the un­cer­tainty. Full de­tails of this and other in­ci­dents can be found at: air­prox­ in the ‘Air­prox Re­ports and Anal­y­sis’ sec­tion.

The C150’s spring-loaded flap se­lec­tor switch does not give the pi­lot a vis­ual clue of the se­lected flap po­si­tion

The the po­si­tion of the C152’s flap se­lec­tor switch in­di­cates what de­gree of flap has been se­lected

Maule Star Rocket (not the ac­ci­dent air­craft) — see ‘Left-hand, right-hand con­fu­sion’

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