Anyone heard of "The Penang Approach"?

[Noyzz]

Hi -

In conversation with another GA Pilot, he told me about a very (very!) steep approach me made in his PA28 when coming in to land. He referred to it as making a "Penang Approach", and did so because he wanted to lose a lot of height quickly.

I've looked on the web, but can find nothing about it. Has anyone else made this type of approach, or have more info about exactly what is involved?

[BackPacker]

I don't know the name specifically, but in general if you need a very steep approach, for whatever reason, use full flaps, fly with the airspeed at the top of the white arc, and put the aircraft in a full-rudder sideslip. That maximizes the drag.

Note that with a full sideslip there's no guarantee that your ASI, ALT or V/S are accurate, so you might want to maintain a bit of margin below Vfe. (And well above Vs, obviously.) In general, you fly the aircraft more by feel, picture and wind noise than by instruments.

And note that certain aircraft, most notably some variants of the C172, do not permit slipping with flaps extended, due to the blanking of the tail assembly by the flaps.

[sapperkenno]

Not heard of the Penang Approach, but here's a good one for a PA28... (maybe this is it?!)

Full flaps, power to idle and 55kts. No need to slip. You come down like a rock, and have just enough of a margin above stalling to round out smoothly. Don't be scared by the "ground rush" and start pitching up early, just keep at 55kts and round out smoothly and firmly at about 20'.


The "Penang" approach is probably more of a corkscrewing dive though, of the type used by the military to avoid anti-aircraft fire. Something like the "steep spiral dive" manoeuvre in the FAA Commercial syllabus.

[Bob the Doc]

I think the approach is called Che Sanh. Approach at medium altitude to avoid small arms fire and then steep nose down, pulling out of the dive in time to get the wheels on the runway. Used in 'Nam on C130s originally. Popular demonstration with military transports at airshows. Usually coupled with a rapid stop with reverse thrust and/or reverse pitch on the props, a reverse down the runway and then getting the hell out of dodge ASAP!

[treadigraph]

Khe Sanh Approach

C-130 Hercules Khe Sanh landing and Take Off - Mildenhall Air Fete - YouTube (http://youtu.be/jw2er9gaeMc)

[Whopity]

I think you are referring to a Quế Sơn Approach. This was an area of Vietnam where heavy fighting took place and the US C130s adopted a very steep approach profile to minimise the effect of small arms fire. Arrive overhead at 10,000ft, wait till the runway disappears under the nose, select full flap and idle power. See here (http://dl.dropbox.com/u/38428747/Hickham.mp4) Not exactly achieveable in a PA28!

[BroomstickPilot]

Hi All,

I think this type of approach gets various names; none of them generally recognised.

I have heard it referred to as a 'Porteus approach', after Ranald Porteus, who used to be Auster's chief test pilot and who demonstrated this kind of approach in an Auster at Farnborough in the late fifties.

BP.

[goldeneaglepilot]

I have heard on several occasions mention of the Sarajevo approach, which was often used in the Bosnian war of 1992 - 1995. Typically a turboproped aircraft would approach the airport at FL100 and at 4.0 DME to the threshold push the nose down, whilst going into Beta to avoid Vne.

An example of the final profile is shown in the video below (this was to avoid small arms fire on approach)

Luftwaffendemonstration, Tansall "Sarajevo Approach" - YouTube

[goldeneaglepilot]

I was there when that happened - the commentary was the funniest I have ever heard.

[Genghis the Engineer]

Look at "obstacle clearance" in the POH, under approach and landing.

G

[mad_jock]

Are you sure it wasn't a "prang" approach?.

ie if you cock it up you will prang it

[strake]

I recall being shown this approach by Bill Burnhope in the mid-eighties at Sywell. I was a fresh PPL and being checked-out on "the poor man's Spitfire", a Beagle Pup. "Now then young Strake" said Bill as we approached the active runway at about 1000ft, "Can you see the numbers?" Well, I just about could as they slid under the nose and told him so. "OK then, the cabin has just burst into flames and here's how we get down quickly". I had no idea what he was about to do but as he pulled beck the power and crossed the controls, we started to slip down at some speed and it dawned on me that he was going to try the impossible (to me) and land us on the runway. Needless to say, we touched down about halfway down the strip and came to a halt soon after. Most impressive and once I had learnt the technique, a very comforting party piece to practice from time to time.

[BackPacker]

Full flaps, power to idle and 55kts. No need to slip.

Actually, I would say DO NOT SLIP in big, bold capital letters. "No need to slip" is a bit understated in that situation.

If you increase (induced) drag by flying just above Vs, and you slip, you are a stall/spin accident waiting to happen.

Personally, I prefer the high-speed variant where you use full flaps and full sideslip, with the speed close to Vfe (but with a margin to allow for ASI/ALT/VS errors).

[Genghis the Engineer]

The static errors in the PA28 are pretty small in a sideslip, I can't see a particular problem there.

But, I agree with "no need to slip" -the PA28, slow with full flap and (in an Arrow) gear down will descend at an angle that is quite steep enough for any reasonable purposes.

I wouldn't, myself, use the high speed variant unless you have a lot of spare runway - what PA28s don't do at-all well is get rid of energy in ground effect.

G

[Halfbaked_Boy]

Is it anything to do with The Penang Reacharound?

[BackPacker]

The static errors in the PA28 are pretty small in a sideslip, I can't see a particular problem there.

Personally I'd be more worried with pitot errors, when slipping close to the stall. Particularly if you use the ASI to figure out what your margin above the stall is, instead of the stall warner and the seat of your pants.

what PA28s don't do at-all well is get rid of energy in ground effect.

True. You will want to stop the sideslip and reduce speed to Vref or thereabouts maybe 50 feet off the ground, well above ground effect, and in time to setup the proper attitude for x-wind compensation.

[Tone]

There is a wonderful story (possibly apocryphal) of a Vulcan doing a wheels-down approach to a flat topped Australian warship which was anchored and minding its own business in Penang Harbour, this would have been in the late 60s, the Vulcan fleet would regularly send one of their number from Singapore to Butterworth for a couple of days to show the flag.

In this case the Penang approach would have been quite worrying to the crew sunning themselves on deck.

[bingofuel]

I recall a similar story when someone flew an unauthorised approach to a carrier, and the crew, thinking it was a real emergency started heaving equipment and aircraft over the side to clear the landing run.

Perhaps someone else can fill in the details?

[treadigraph]

Bingofuel, that has to be the apocryphal story about the Shackleton crew on a long and dreary patrol far out over the Atlantic in the 1950s, who espied a US Navy carrier through a small gap in the clouds. Quick bit of plotting by the nav and they emerged from the cloud nicely lined up with the deck, gear and flaps dangling... Brand new jets over the side to make space for the "emergency", horrified and embarrassed Shack disappeared as rapidly as possible back into the clag.

Regarding the Porteous Approach, is that confusion with the Porteous Loop with which featured a flick roll at the top, better known these days as an avalanche?

[BroomstickPilot]

No, I don't believe it is.

Porteus was known for both and I saw him do both.

(I'm giving my age away)!

BP.