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Aviation Learning Center Document Descent to MDA or DH and Beyond - P-8740-09
Author: Federal Aviation Administration Date: 1996
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Preflight Preparation
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Call Flight Service

When talking to an Automated Flight Service Station (AFSS) briefer, be sure to get all notices to airmen (NOTAMs) pertaining to your flight. These include local NOTAMs (NOTAM-L) for departure and destination, distant NOTAMs (NOTAM-D), and - vital for IFR flight - flight data center (FDC) NOTAMs. Be sure to get not only current NOTAMs, but also those already published in the bi-weekly NOTAMs. If you are using direct user access terminal (DUAT) for your weather briefing information, you will need to use a site-specific airport identifier to get FDC NOTAMs. It may be necessary to call the AFSS to be sure that you have the NOTAMs already published in the bi-weekly NOTAM publication. You might also want to call your destination airport to see if there are any special local "Letters to Airmen" that could affect your flight.

Review Charts

After obtaining a weather briefing and determining which runway is likely to be in use at your destination, review all possible approach charts. Be sure to note any obstructions and their location relative to the airport.

Make sure that you have current enroute, approach, and sectional charts on board. It is not a good idea to switch back and forth between National Aeronautical Charting Office (NACO) and Jeppesen charts; choose one format and use it on a regular basis to ensure that you know exactly where to look for the information you need at any given time. An aircraft cockpit is not the place to familiarize yourself with a chart format that you are not accustomed to using!

You will also want to have all of the approach charts for your destination airport (and also your alternate, if one is required) readily available. Trying to find the right chart when you are also flying the aircraft in instrument meteorological conditions (IMC), especially in single pilot operations, is not consistent with either good judgment or good planning.

Know what your options are with respect to the approach procedures. If the ILS glideslope (GS) fails, are you ready to fly the localizer (LOC) approach? Are you proficient enough with your equipment to fly a GPS approach? Is your equipment legal to use on a GPS approach? Are you equipped -- and proficient -- enough for VOR/DME or NDB approaches? Think through these points in advance. If you do not have the equipment required or the training needed to fly one or more of the approaches at your destination, the best time to figure that out is on the ground. Now is a good time to ensure that all the navigational aids in your aircraft -- VOR, GPS, DME, ADF -- are working properly.


With the advent of satellite navigation, instrument pilots today have a number of new terms to understand on instrument approach procedure charts. It is extremely important for you to understand what these terms mean, and whether your aircraft is equipped to use these minimums. The graphic below is from Figure 5-15 in FAA-H-8261-1, Instrument Procedures Manual.

RNAV Vertical Guidance

It is a good idea to review the FAA Instrument Procedures Manual (FAA-H-8261-1) to be sure that you fully understand these terms, but here are a few definitions:

  • RNAV: This term refers to "area navigation." There are many different levels of authorizations for use of RNAV approach systems. Factors determining the level of authorization include the type of equipment installed in the aircraft, the redundancy of that equipment, its operational status, the level of flight crew training, the level of the operator's FAA authorization, etc.

  • APV: Approach with vertical guidance.

  • VNAV: VNAV stands for "vertical navigation." Authorization to use VNAV on a conventional nonprecision approach, RNAV approaches, or LNAV/VNAV approaches is found in that operator's OpsSpecs, AFM, or other FAA approved document. Important: Do not assume that a GPS navigator with VNAV capability will produce glideslope-like vertical guidance. On many common GPS navigators, the VNAV function is only a descent planning and situational awareness tool. Know your equipment!

  • LNAV: LNAV stands for "lateral navigation" LNAV minimums are provided for RNAV systems that do not produce any VNAV information. Because vertical guidance is not provided, the procedure minimum altitude is published as an MDA. These minimums are used in the same manner as conventional nonprecision approach minimums. Other RNAV systems require special approval.

  • LPV: LPV is not an acronym, but you might think of it as "localizer performance with vertical guidance." The term refers to APV minimums that use Wide Area Augmentation System (WAAS) to provide electronic vertical guidance capability. Important: Your aircraft must have WAAS avionics equipment approved for these approaches in order to fly to LPV minimums.

  • LNAV/VNAV: Minimums listed as LNAV/VNAV are APV minimums used by aircraft with RNAV equipment that provides both lateral and vertical information in the approach environment, including WAAS avionics approved for LNAV/VNAV approaches, certified barometric-VNAV (Baro-VNAV) systems with an IFR approach approved GPS, certified Baro- VNAV systems with an IFR approach approved WAAS system, or approach certified RNP 0.3 systems. Minimums are shown as DAs because the approaches are flown using an electronic glidepath. Other RNAV systems require special approval.

List Your Information Sources

From the approach charts and the Airport/Facility Directory A/FD, determine whether radar is available. You may also want to know the Minimum Vectoring Altitude for the destination area, to determine if a visual or contact approach is possible.

Find out what sources of weather reporting exist at your destination: ATIS, AWOS, ASOS, etc. and be sure that you have the frequencies for each one readily available.

Review Personal Minimums

Before departing, review your personal minimums and compare them to conditions you expect at departure, while enroute, and at your destination. Take into account how current and proficient you are, your experience level, and your familiarity with the aircraft and its systems. If you are a relatively new instrument pilot, set your minimums high - possibly even VFR or MVFR conditions - until you gain experience in the system, and in the type of aircraft and equipment you will operate. In addition, keep in mind that personal minimums may need to change on any given day. If, for example, you are flying an unfamiliar airplane, or if you are tired from a long day at work, you may not want to attempt low approaches.

Make an Escape Plan

One of the most important things to do in your preflight planning for IFR flight is to find, and plan, your escape route. Don't launch your flight without knowing where to find the nearest present, or forecast, VFR weather that is within range of your aircraft. You might also find it helpful to identify a suitable airport for each 20-30 mile segment of your route. The VFR escape plan could also be very useful in a lost comm situation. (Note: It's a good idea to review lost comm procedures from time to time.)

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