Careful planning for a flight on instruments is important. Besides satisfying normal IFR requirements, an instrument pilot flying in clouds or at night must be conscious of high terrain or obstacles that cannot be seen, and ensure that a safe altitude above them is maintained. You must be aware of the danger of icing (both airframe and carburetor icing) and take appropriate precautions; you must have an alternate airport in mind in case a diversion becomes necessary; and you must have sufficient fuel to get there, and still have a safety margin remaining in the tanks on arrival.
The best time to organize these things is prior to flight.
Today, we’ll discuss preflight considerations for an IFR flight with excerpts from our textbook The Pilot’s Manual: Instrument Flying (PM-3C).
Preflight considerations, which are all logical, include:
- Am I properly qualified (instrument rated and qualified for this airplane, instrument current)?
- Am I medically fit today?
- Is the airplane suitably equipped (serviceable radios, anti-icing equipment, lighting, etc.)?
- What is the weather? Are changes expected?
- Is the departure airport suitable for my operation?
- Is the destination airport suitable for my operation?
- Is an alternate airport required (or more than one)?
- What routes are suitable in terms of terrain, weather and available en route NAVAIDs?
- Are there any relevant NOTAMs (FDC, Class I, Class II)?
- Are there any Terminal Flight Restrictions (TFRs) for my planned route of flight?
- Prepare charts (DPs, en route charts, instrument approach charts, VFR sectionals, etc.).
- Compile a flight log with courses, distances, times, MEAs and cruising altitudes calculated.
- Compile a fuel log, with adequate fuel reserves.
- File an IFR flight plan.
- Prepare the airplane.
- Organize the cockpit for flight—select charts, ensure that a flashlight is kept handy for night flying, etc.
- Brief passengers.
To operate in controlled airspace (Classes A–E) under IFR, you are required to:
- file an IFR flight plan (usually done in person or by telephone to FSS or ATC on the ground at least 30 minutes prior to the flight); and
- obtain an air traffic clearance (usually requested by radio immediately prior to departure or entering controlled airspace).
The 30 minutes is required to allow time for ATC to process your flight data and (hopefully) avoid delays to your flight. The preferred methods of filing a flight plan are: in person by telephone or by DUATs — by radio is permitted, but discouraged because of the time it takes. Closing a flight plan by radio is typical because it takes just a few seconds.
Closing an IFR flight plan is automatically done by ATC at tower-controlled airports after landing. At an airport without an active control tower, you must close the flight plan with FSS or ATC by radio or telephone. Do this within 30 minutes of the latest advised ETA, otherwise search and rescue (SAR) procedures will begin.
- An IFR flight plan is required in both IMC and VMC in Class A airspace, and in IMC conditions in Classes B, C, D and E (controlled) airspace (and also in VMC, if you want to practice);
- An IFR flight plan is not required in Class G (uncontrolled) airspace.
To assist you in completing the flight plan and performing the flight, you should compile a navigation log, calculating time intervals and fuel requirements. A typical navigation log is shown in figure 1, and a typical flight plan form is shown in figure 2.
Figure 1. Click for full-size.
Figure 2. Click for full-size.
Important navigation log items to be inserted on the flight plan include:
- the planned route;
- the initial cruise altitude or flight level (later altitudes or flight levels can be requested in flight);
- the estimated time en route (ETE), in hours and minutes, from departure to touchdown at the first point of intended landing;
- the total usable fuel on board at takeoff, converted to endurance in hours and minutes.
If you wish to fly part of the route according to IFR procedures and part according to VFR procedures, you can file a composite flight plan, signified by you checking both IFR and VFR in the Item 1 box on the flight plan form. You should also indicate the clearance limit fix in the flight-planned route box, to show where you plan to transition from IFR to VFR.