An instrument approach plate is a compact map and procedure guide that helps a pilot fly safely from the enroute environment to a runway when outside visual references are limited. It organizes navigation, altitudes, courses, distances, frequencies, and landing minimums into a standard layout. Reading it correctly matters because every number on the chart supports terrain clearance, obstacle avoidance, and a stabilized arrival.
The plate is not just a picture of a path, it is a legal procedure that must be briefed and followed precisely.
Key Facts
- Required descent rate for a 3 degree glide path is approximately descent rate = ground speed x 5.
- Minimum Descent Altitude, MDA, is used for nonprecision approaches and must not be descended below until visual requirements are met.
- Decision Altitude, DA, is used on precision approaches and is the altitude where the pilot decides to continue or go missed.
- Distance to runway can be estimated by time = distance / ground speed, with consistent units.
- Missed approach point, MAP, is the point where the pilot must begin the missed approach if landing conditions are not met.
- Course intercept planning uses heading correction angle approximately equal to drift angle plus intercept angle.
Vocabulary
- Approach Plate
- An approach plate is a published chart that gives the instructions and limits for flying an instrument approach to a runway.
- Plan View
- The plan view is the overhead map portion of the chart that shows fixes, courses, navigation aids, and the missed approach path.
- Profile View
- The profile view is the side view of the approach that shows step-down fixes, altitudes, distances, and descent path information.
- Minimums
- Minimums are the lowest altitude and visibility values allowed for continuing an approach to landing.
- Fix
- A fix is a defined position in space identified by GPS, radio navigation, distance, or crossing information.
Common Mistakes to Avoid
- Confusing MDA with DA is wrong because an MDA is a hard altitude floor while a DA allows an immediate transition to the missed approach after the decision point.
- Ignoring the missed approach instructions is wrong because the missed procedure must be ready before descent, not figured out after losing the runway environment.
- Reading only the plan view is wrong because the profile view contains the vertical restrictions needed to avoid descending too early.
- Using the wrong minimums line is wrong because aircraft category, approach equipment, and runway lighting can change the legal visibility and altitude requirements.
Practice Questions
- 1 An aircraft is flying an approach at 120 knots ground speed on a 3 degree glide path. Estimate the required descent rate in feet per minute using descent rate = ground speed x 5.
- 2 A nonprecision approach has an MDA of 860 feet MSL and the airport elevation is 420 feet MSL. What is the height above touchdown zone or field elevation, assuming field elevation is used?
- 3 A pilot reaches the missed approach point with the runway not in sight, but the aircraft is stable and on course. Explain what the pilot should do and why the approach plate must already have been briefed.