Cross-Check Techniques: IFH Chapter 4

Handbook Reference

IFH Ch 4

4.cross-check-techniques. Cross-Check Techniques (Instrument Scan)

Cross-checking, also called scanning or instrument cross-check, is the continuous and logical observation of the flight instruments for attitude and performance information. It is the first of the three fundamental skills of attitude instrument flying — cross-check, instrument interpretation, and aircraft control. Without an effective scan, the pilot cannot detect deviations early enough to make small, smooth corrections, and instrument flight quickly degrades into chasing the needles.

There is no single 'correct' scan pattern that fits every maneuver or every pilot. The scan must be tailored to the maneuver being flown and to the instruments that provide the most pertinent information for that maneuver. The Instrument Flying Handbook describes two broadly accepted methods.

Selected Radial Cross-Check

In the selected radial cross-check, the pilot spends 80–90 percent of the scan time looking at the attitude indicator (AI), breaking off only to take quick glances at the other flight instruments — heading indicator, altimeter, airspeed indicator, vertical speed indicator (VSI), and turn coordinator. After each glance, the eyes return to the AI before moving to the next instrument. The path resembles spokes radiating from the hub of a wheel, with the AI at the center.

This radial pattern works because the AI is the only instrument that provides an immediate, direct picture of both pitch and bank. By using it as the reference, the pilot interprets the supporting instruments in context rather than jumping randomly between them.

Inverted-V Cross-Check

A simplified version of the radial scan, the inverted-V pattern moves the eyes from the AI down to the turn coordinator, back up to the AI, then down to the VSI, and back to the AI. It is most useful during initial training to build the habit of always returning to the attitude indicator.

The Rectangular Cross-Check

A rectangular pattern sweeps the six-pack in order — across the top row (airspeed, AI, altimeter), then across the bottom row (turn coordinator, heading indicator, VSI), then back up. It exposes the pilot to every instrument but does not weight the AI as the primary attitude reference, so it is generally discouraged as a habitual pattern.

Common Scan Errors

The IFH identifies several errors that destroy an otherwise good cross-check:

Fixation — staring at a single instrument. A pilot who locks onto the altimeter while trying to recapture altitude will often allow heading or bank to drift unnoticed.
Omission — leaving an instrument out of the scan, commonly the VSI or turn coordinator. Trends on the omitted instrument go undetected.
Emphasis — placing too much weight on one instrument while still checking the others, for example flying the heading indicator instead of the AI in turbulence.

All three errors share the same root cause: the pilot stops using the AI as the control instrument and starts trying to fly the performance instruments directly.

Scan Rate and Maneuver

Scan rate must match the maneuver. In straight-and-level cruise with the autopilot off, a relaxed scan with frequent returns to the AI is sufficient. During an instrument approach, configuration changes, intercepts, and altitude captures demand a faster, more disciplined cross-check, with particular attention to the instruments most relevant to the current segment — for example, the CDI and altimeter on final, or the heading indicator and turn coordinator while intercepting a course.

The pilot should also include the power instruments (manifold pressure or RPM, and on turbine aircraft, EPR or N1) in the scan. Pitch + power = performance, and ignoring power settings is a frequent cause of altitude and airspeed excursions.

Building an Effective Cross-Check

The IFH recommends the following habits:

Always return the eyes to the attitude indicator between other instruments.
Move the eyes, not the head — head movement increases susceptibility to spatial disorientation, particularly the Coriolis illusion.
Trust the instruments. If a single instrument disagrees with the others, suspect that instrument, not the cluster.
Cross-check trends, not just current values. A VSI showing 100 fpm down predicts an altitude loss before the altimeter moves enough to notice.
In a glass cockpit (PFD), the AI is enlarged and the supporting tapes (airspeed, altitude, vertical speed, heading) surround it, which naturally enforces a radial scan but can also induce fixation on the magenta line of the flight director. The same scan discipline applies.

Example

Level cruise at 5,000 ft, 110 KIAS, heading 090°. The pilot notes pitch and bank on the AI, glances at the altimeter (5,000), back to the AI, glances at the heading indicator (090°), back to the AI, glances at the airspeed (110), back to the AI, glances at the VSI (0), back to the AI. A 50 ft altitude deviation is caught on the next altimeter sample, corrected with a small pitch change on the AI — not by staring at the altimeter until it returns.

Mastery of the cross-check is what allows instrument interpretation and aircraft control to occur almost subconsciously, freeing the pilot's capacity for navigation, communication, and decision-making.

Oral Exam Questions a DPE Might Ask

Q1What is the selected radial cross-check, and why is the attitude indicator at its center?

It's a scan pattern in which the pilot keeps the eyes on the attitude indicator most of the time, breaking off briefly to sample each supporting instrument and returning to the AI between each glance. The AI is central because it's the only instrument that gives a direct, immediate picture of both pitch and bank — the foundation of aircraft control.

Q2Name the three most common cross-check errors and how each shows up in flight.

Fixation — staring at one instrument so deviations elsewhere go unnoticed; omission — leaving an instrument out of the scan, often the VSI or turn coordinator, so trends are missed; and emphasis — over-relying on one instrument such as flying the heading indicator instead of the AI in turbulence. All three break the discipline of returning to the attitude indicator.

Q3How should your scan change when transitioning from cruise to an instrument approach?

The scan rate increases and the weighting shifts toward the instruments most relevant to the current segment — CDI, altimeter, and airspeed on final, with frequent returns to the AI for control. Power instruments are also included more actively because configuration changes during the approach demand precise pitch-and-power coordination.