Instrument Insights Part 8 of 12

Tricks of the Trade

August 1, 1998

Finding flexibility on IFR flights

To many, flying IFR may seem like an exercise in passive compliance within a complex maze of strict, unwavering rules. However, that's not really true. The Federal Aviation Regulations (FARs) and the Aeronautical Information Manual (AIM) provide instrument pilots a number of time- and fuel-saving methods of working the system to their advantage. Here's a look at some of the more useful.

Composite flight plan

This type of flight plan lets you split your flight into two segments: one under VFR, the other under IFR. Let's say that the first part of your flight will be in good weather, but that you'll run into instrument conditions before reaching your intended destination. It's perfectly legal to file a VFR flight plan for the part flown in visual meteorological conditions (VMC), then have an IFR flight plan waiting for you to activate when you approach instrument meteorological conditions (IMC).

To fly on a composite flight plan, you simply file with flight service as you normally would, but name an intermediary fix as the point where the first part of your flight plan ends and the second begins. This could be a VOR or other navaid, or an intersection.

If the first part of the flight will be conducted under VFR, then call flight service after departure to activate the flight plan. Before reaching the fix that you've named, radio the nearest flight service station — not flight watch — to pick up your instrument clearance. You must remain in VMC, and fly under VFR until you've received your IFR clearance and have begun flying in accordance with the instrument clearance. Now you're legal to fly in IMC and continue on.

Don't forget to cancel the VFR part of your flight plan with FSS or ATC!

It also works in reverse. If the first part of the flight will be under IFR, then you proceed to your clearance limit — again, a navaid, intersection, or other fix — and then tell ATC that you want to cancel your IFR flight plan. Then it's time to radio flight service to activate the VFR part of the flight plan.

Let's say that the forecast for VFR weather advertised for the second part of your trip goes bust. You can remain on your IFR flight plan if you call ATC five minutes before your clearance limit and receive a clearance extension. If you don't have the new clearance by the time you reach the clearance limit, then you'll have to fly in a holding pattern at the clearance limit fix until you're cleared for the rest of the trip.

You don't hear much about composite flight plans, but they can be extremely useful. When it's VFR, you can fly direct. When it's time to face IMC, you'll have the safety advantage of an instrument clearance.

Contact approach

This shortcut comes with two big, fat warnings: (1) It's legalized scud-running; and (2) It works safely only if you are completely familiar with local terrain. Most instrument pilots won't fly them, and contact approaches can be scary for the inexperienced.

Maybe that's why pilots have to initiate a request for a contact approach. Controllers, by regulation, cannot ask pilots to perform them.

So what's a contact approach? It's an approach to an airport with a published instrument approach that's flown by reference to the ground. Now get this: To fly it, you need a visibility minimum of one statute mile, as reported by the destination airport, and you have to fly clear of clouds. It's Special VFR in another guise, if you will.

The pilot is responsible for obstruction clearance (that's why you need to know the terrain), but ATC will provide you with separation from other IFR or Special VFR traffic.

It's useful only when you need to go short distances in relatively uncomplicated, low-density airspace. Try to ask for a contact approach into LAX or JFK and you'll probably be laughed off the frequency.

The AIM emphasizes that the contact approach is meant only as a substitute for a standard instrument approach. You can't use it as a poor man's IFR approach to an airport not having a published approach procedure. Nor can you use it to approach one airport, break off the approach, and then fly to another airport.

Visual approach

If the ceiling and visibility at your destination is at least 1,000 feet and three miles, then pilots on instrument flight plans can ask for a visual approach. Likewise, controllers can assign visual approaches when these conditions prevail.

Like a contact approach, a "visual" lets you fly to the runway without having to perform an instrument approach, and you must remain clear of clouds. But the weather minimums are higher.

Before being cleared for a visual approach, ATC will ask you if you have either the airport or preceding traffic in sight. With the airport in sight, ATC can clear you to land just as it would in good VFR conditions. In this case, it's usually best to make a beeline for the approach end of the active runway — although you can make a standard traffic pattern to a landing.

ATC can also give you a visual after you identify an airplane ahead of you in the landing sequence. Once you tell the controller that you've got the traffic in sight, you'll be told to follow that airplane to the airport. Catches? They're minor: You have to maintain safe separation from the traffic that you're following, and it's up to you to avoid any wake turbulence that might be created by the airplane landing ahead of you.

With the exception of the visual approach, these shortcuts are seldom used, and they're seldom — if ever — taught by instrument instructors. Even so, they can be essential tools in an instrument pilot's bag of tricks, and may be lifesavers when the chips are down and you need to legally cut some corners.


E-mail the author at tom.horne@aopa.org.