Wednesday, March 22, 2006

Contact Approaches

I'm studying up stuff I don't do much in order to prepare for my training and proficiency check. I don't think I've ever done a contact approach. It can be a dangerous maneuver.

An aircraft on an IFR flight plan can follow instrument indications almost all the way to the runway (a precision approach) or to the immediate vicinity of the airport, descending further only if the runway is in sight (a non-precision approach). It is possible also to remain on an IFR flight plan yet stop navigating by instruments and start navigating by looking out the window, before reaching the airport.

If the weather is good -- at least 3 sm visibility, and ceiling at least 500 feet above the minimum IFR altitude -- and the pilot sees both the airport and any traffic which she is supposed to be following, ATC can clear her for a visual approach. She finds the airport, flies to it and lands. She is respnsible for wake turbulence separation, noise abatement procedures, and looking out for VFR traffic. There is no published missed for a visual. If weather might bring on the need to miss the approach then the pilot should not accept a visual approach. A visual is easy. I do those a lot. The weather limits are equivalent to those required for VFR flight in controlled airspace.

If the weather is lousy, and the pilot can't see the airport, but thinks she can find it, she can ask for a contact approach. The visibility has to be at least one nautical mile, the very minimum allowed for VFR flight. The aircraft must be flown at least 1000 feet above the nearest obstacle within five nautical miles of where the pilot thinks she is. The airport must have a published instrument approach. Pilots are cautioned to be familiar with the local terrain and noise abatement when attempting this kind of approach. I think some companies forbid them.

I've just made that sound really sketchy, but there are times when a contact approach can be safe and useful. Your airport is on the shore, and there's always a bunch of cloud right around the MDA. You are at the MEA, but you can't see the airport. You request descent to the MOCA, but you still can't see the airport, although you can see the shoreline and recognize the geography telling you you're almost there, and the AWOS says you have at least a mile in mist at the field. You ask for a contact approach, descend out of the MEA and follow the shoreline until you have the airport in sight and then you turn and land. I guess the contact approach is meant to fill in the gap between cancelling IFR when there's a chance the flight can't be completed VFR, and turning away from an airport where you could land perfectly well if it weren't for the stupid rules.

And I've probably used this joke before, but it fits.

"Centre, Barnburner One, request the visual approach."
"Barnburner One, confirm you have the airport in sight?"
"Uh, negative Centre, but we know where it is!"


david said...

I flew a contact approach into Sault Ste. Marie once, nearly two years ago. We hit severe turbulence in at TCU on a localizer backcourse approach, managed to get out and underneath, then took a long contact approach from the end of Lake Huron along the St. Mary's River to the airport to stay out of cloud. In the future, I'd probably choose Special VFR over a contact approach under the same circumstances, since the minima aren't as strict.

paul said...

Isn't this about the same as a circling approach?

I guess in a circling approach if I loose site of the runway I am to execute the missed procedure, except I was more or less on downwind...


Greybeard said...

I take off for a few days, and everything falls in your lap!

First, congratulations......
then, did I hear you right...
Vole's location was bad, Vizcacha's was worse?

As a helicopter jockey, I have no idea what "weedwhacker" is. I'm slightly familiar with recip engine airplanes, so I have an idea. Guess it really doesn't matter too much-
a stepping stone for you toward heavy iron in the future.

Being patient has it's rewards.
I'm delighted to be able to follow your triumphs via "Cockpit Conversation"!

John said...

Congrats on the new job and best of luck.

Contact approaches ... the rules in the US are slightly different, but the idea is the same. I call it "special IFR." I'd have to be pretty desperate to ask for a contact approach. Can't imagine a scenario where I'd do one on my own and my company does not allow them. Other than that, they're great!


IJ said...

Have never heard of the contact approach before! In the UK we just have VFR approach (which is a visual but not Visual... can be assisted by navaids or vectors if in a busy environment), Visual approach (IFR Visual approach... pilot can see aerodrome, traffic he's following, told to remain clear of noise sensitive areas), then the instruments approaches - ILS, NDB, VOR, xxDME, MLS, PR-NAV (new!).
If flying SVFR, you are expected to an approach as a VFR would... unless a helicopter (can fly SVFR in certain zones with practically no vis).

Anonymous said...

Contact approach is for the transport aircraft that can see the airport from thirty miles away and wishes to conduct his/her approach visually while still remaining IFR. A good example would be when the runway in use is ninety degrees to the inbound track. This would allow the pilot to go below MOA's and make it possible to turn final closer in, saving time and fuel. It has the added bonus of allowing a hand flown approach on a nice sunny day!

Aviatrix said...

If you can see the airport, you'll likely be offered the visual. Usually that's the one that's on the AIS on a nice sunny day anyway.