Plane crash Caernarfon

[mad_jock]

come on you can hardly be surprised with the reputation that the owner has.

Must admit all I saw was blackpool, dodgy maint along with suspect procedures taught by an instructor.

Looked up G-INFO and low and behold my suspicions where correct.

[Shaggy Sheep Driver]

Misuse of hot air control looks like being the primary cause, but what about that approach profile for a SEP? 4nm? Long, low...

Don't today's flying instructors know that hot air needs to be applied for quite a long time be effective, and should only be de-selected on short final in case a late go-around is called for? Or de-selected with power application in the event of an earlier go-around? Otherwise it should be ON in the circuit!

Whack on the hot air, wait a few seconds, whack it off... You probably make matters worse by doing that!

And those bomber approaches. ...Why?

We're not flying an airliner on an instrument approach - it's a light single in VFR! Keep it tight! Keep your height as long as you can!

[piperboy84]

Is there any downside whatsoever (other than a slight reduction in power) of having the carb heat on upon entering the pattern and leaving it on all the way till short final every time regardless of air moisture/temps?

I ask because back in the day when i was training one instructor advised to put carb heat on on the downwind to "test" to see if it was needed and if not return it to cold, another said just leave it on till just prior to touchdown or go around.

Its pretty hard to expect a pilot to have a mental picture of that carb icing envelope chart in his head and decide if conditions apply, so why no just leave it on all the way round?

[Shaggy Sheep Driver]

It's theoretically possible for carb heat raise the inlet temp into the carb ice range, but pretty unlikely. Generally, the only downside is a reduction in power.

On the dHC1, warm air (as opposed to hot air) is generally always selected 'on' except at take off. RAF Chippys had it hard-wired to 'warm', with no 'cold' option. But then Brenda's Boys operated from nice long runways!

[Cows getting bigger]

A quick look at the POH for a Cherokee 140 reveals a bit of advice which conflicts with 'best practice' - "carburettor heat should not be applied nless there is an indication of carburettor icing" - this is standard POH guidance for PA28s.

A few years back I used to frequent a leaky hangar at the West end of Aodergrove. Hidden towards the back was GATRR, covered in guano and obviously not flown, for a long time. To think that someone declared this aircraft airworthy and, somewhere along the way, it 'lost' a couple of rear spar bolts without anyone noticing is shocking. As for the 50/150 confusion - outrageous.

Of course, the crash most probably wasn't caused by slack engineering procedures but, to me, this event highlights that we appear to be happy to launch into the sky in rubbish we would never consider driving down the road.

[cockney steve]

I'm with SSD on this, purely from a mechanic's perspective.
Heat will tend to soak back from the cylinder to the manifold , therefore, other than carburettor -ice, I'd expect any formation to be part-way along the induction-tract....but the carb. venturi would tend to freeze the moisture out first......add carb heat, -FUNDAMENTAL TEACHING, - If engine runs rougher, it's carb ice melting LEAVE HEAT ON !!!! A carb with fixed-mixture may actually run better, as the heat will lean the mixture slightly .. the effect of the warm-air blast on ice is probably only a few seconds before it starts to melt, However, As SSD suggests, It would probably take in excess of 10 minutes at lowish power-settings, to heat-soak the Carb. body to any useful degree.
For my money, carb heat in the circuit if there's the slightest chance of ice formation....bung it in on short final and you can be confident a clump of ice is not going to spoil a sudden decision to go-round....On a short strip, that sudden cough and splutter could be a really bad thing.
The loss of power with heat is not that big-a -deal, IMO, as the aircraft is not taking -off, so it's got less drag and needs less power (also may be in ground-effect) It's by far the lesser evil. momentary application of carb heat can be dangerous, as explained above...a monimum of 30 seconds should be about right. to be certain..

The only downside, other than the small power-loss, is the fact the warm air is unfiltered, but the air is relatively clean aloft, compared with ground-level and tyres and turbulence stirring up dust....carb heat still makes sense as a wise precaution.

[piperboy84]

Another thing I noticed looking at the track was it appeared to be a a non standard approach, the join made on the "base" leg was more like a 45 degree join for final, not that this caused the accident but I wonder if joining on a definitive part of the circuit either downwind or base with the standard 90 degree turns would afford a better and more familiar judgement of altitudes and speeds needed in case a dead stick landing had to be made, also check list sequencing based on pattern location me be thrown off with non standard pattern entry and approach.

Just a thought about entering the pattern in general and not criticizing the pilots in this accidents airmanship in any way.

[CaptainChairborne]

I'll criticize his airmanship. The pilot had 90 hours accrued between January 2005 and and May 2013, and as I read it, hadn't revalidated/renewed his licence which had lost its validity on 14th April 2012. I think inexperience and lack of currency could have been a contributing factor. Looking at the track on final in figure 5 of the report, he seems to have been aiming for the end of the runway rather than the displaced threshold - though I'll grant the photo may not be accurate

[flybymike]

A carb with fixed-mixture may actually run better, as the heat will lean the mixture slightly .

Warm air is less dense than cold air, so application of carb heat will enrichen the mixture.

[Pull what]

and 3 degree approaches are not appropriate for light VFR singles except under unusual cirmstances.

This is the sort of grass airfield Tiger Moth folk lore that has been around for far too long.

If you can fly a 3 degree glidepath in a large transport aircraft why can you not fly similar in a light aircraft?

VFR? So its OK to fly an ILS while IFR or in IMC at 3 degrees were you may not be able to see any approach obstructions but its not when you are VFR, how ridiculous.

So its OK to take a 747 over obstructions on the approach on a 3 degree glidepath but you need to be higher in a light aircraft?

(This is where they usually trot out that old chestnut about if the engine fails you wont make the airfield on a 3 degree glidepath but even that has been proved wrong at Heathrow)

3 degrees is generally the minimum approach angle were clearance above obstructions in the approach funnel is guaranteed. 3 degrees is perfectly acceptable in any aircraft were a 3 degree glidepath can be flown. Its amazing how many instructors quote this 3 degree myth but then go out and teach use of 3 degrees with VAPI and PAPIs at NIGHT!

Caenarfon was shown in the AIP as having trees(since removed I believe) as an aerodrome obstruction on the approach to runway 26 at the time of the accident.

There is a common tendency for pilots to duck under the glidepath at any approach angle were displaced thresholds exist and this, coupled with the focus going from the approach to the touchdown point in the latter stages, means that approach obstructions are sometimes overlooked. This ducking under tendency is also seen more often at unfamiliar airfields or on performance limiting runways. Ive seen it happen in both large transport aircraft and light aircraft. Ive also even heard an instructor teaching students to always aim at the first of the two displaced threshold arrows to achieve an early touchdown, more ridiculous folk lore!

[Fostex]

When I fly SEP I don't fly a 3 degree approach for the simple reason that it means I will be lower on final than I need to be. If I fly a steep approach and experience an engine failure on base or final I will have the option to glide into the field and will have more time available to locate a site for a forced landing should it be necessary.

There is always the argument that these steep, glide approaches are bad for an SEP due to shock cooling but if the airfield is surrounded by densely populated or hazardous terrain it is the best option.

At the end of the day you fly the approach that is appropriate for the aircraft, traffic and airfield.

[OpenCirrus619]

Originally Posted by Pull what

This is the sort of grass airfield Tiger Moth folk lore that has been around for far too long.

I must disagree. I won't detail what I think of this comment

2 points:

• Only having one engine IS VERY relevant
• A large jet, clean, will achieve in excess of 20:1 (3 degree)glide angle. A small GA SEP around 10:1 (6 degree)

I think the 2nd FACT alone is enough to completely debunk the rubbish above.

OC619

[flybymike]

I support the rubbish above.

[Pull what]

I support the rubbish above.

Me too!!!!!

[mad_jock]

bloody hell the nursing home have let him at the internet again.

Just put him (pull what) on your ignore list and you will be happy again.

Remember

there are some sad individuals who like to play walter mittys and seem to get pleasure out of arguing the toss on here.

[piperboy84]

IMHO, the steeper the better, nice and slow, with a quick and slight burst of power upon entering ground affect, eyes doon the strip and kiss the ground as smooth as a baby's bum !!

[Shaggy Sheep Driver]

Someone show him that super video, you know, the one with the '3 degree' captain with epaulettes all the way up each arm! It's brill and it puts ****e like what Pull What is pedaling in its place - in the toilet!

[Genghis the Engineer]

Originally Posted by OpenCirrus619

I must disagree. I won't detail what I think of this comment

2 points:

• Only having one engine IS VERY relevant
• A large jet, clean, will achieve in excess of 20:1 (3 degree)glide angle. A small GA SEP around 10:1 (6 degree)

I think the 2nd FACT alone is enough to completely debunk the rubbish above.

OC619

I agree also.

The only good reason I can think of to fly a 3 degree in an SEP is practicing for the occasional IAP. Any other time, it's an unnecessary manoeuvre.

Third point - staying higher longer and using less power on approach annoys the noise-sensitive neighbours less.

Fourth point - practicing low power approaches is useful practice ust in case one day you need to do one for real.

G

[Fostex]

Here we go, I show this to everyone I see flying their big jet stabilised approaches in a spam can.

http://youtu.be/f6q2VKsvQEQ

[cockney steve]

Steep approach, you have energy to spare and the means to dump it once it is no longer required.

Shallow approach, the bag's empty, if you're not carrying enough height and the donkey goes sulky

Which would appear to bring us back to the subject of the thread.