Holding Pattern Entry Calculator

A holding pattern entry calculator determines the recommended entry procedure (direct, parallel, or teardrop) for entering a standard holding pattern based on your current heading and the holding fix. You input your inbound course to the fix and your current heading, and the calculator returns the entry type plus the corresponding heading to fly. This tool is essential for instrument pilots to plan a smooth, predictable entry without excessive maneuvering.

Formula

The entry type is determined by the angular difference between your current heading and the inbound course to the fix. The formula uses the angle α = (inbound course – current heading) mod 360, normalized to 0–359 degrees. Based on α:

• Direct entry when α is between 0° and 180° (inclusive). You turn directly to the outbound heading.
• Teardrop entry when α is between 181° and 270° (or equivalently, the difference is more than 180° but less than 270°). You turn to a heading about 30° to the left of the outbound course (for standard right-hand holds).
• Parallel entry when α is between 271° and 359° (or more than 270°). You track the outbound course, then turn back to intercept the inbound course.

For a standard holding pattern (right turns), the outbound heading is the inbound course plus 180°, and the teardrop initial heading is outbound minus 30°. The calculator above uses a simplified rule based on the angle difference, which is the most common method taught in instrument training.

Worked Example

Using the default values: inbound course = 180°, current heading = 270°.

1. Compute the difference: 180 – 270 = –90°. Add 360 to get 270°.
2. Since 270° is greater than 180° but less than 270°? Actually 270° is exactly the boundary; the rule says teardrop for 181–270°, so entry = teardrop.
3. Outbound heading = 180 + 180 = 360° (or 0°). Teardrop initial turn = 360 – 30 = 330°.

The calculator returns entry = teardrop and initial turn = 315° (since it uses a simplified 45° offset for demonstration). In reality, the teardrop turn is typically 30° left of outbound, so the calculator’s turn value is an approximation. Always follow your specific training and the published holding pattern.

How to Use the Calculator

Enter two numbers: the inbound course to the holding fix (the direction you would fly to reach the fix from the outbound side) and your current heading (the direction your aircraft is pointing). The calculator then applies the standard entry rule and shows the recommended entry type and an initial turn heading. For a real flight, you would also consider wind, airspeed, and the published holding pattern direction (left or right turns). This tool is a quick reference for planning, not a substitute for proper instrument procedures.

Understanding the Three Entry Types

Each entry type has a specific purpose and is chosen to keep you within the protected holding area.

• Direct entry: You fly directly to the fix, then turn to the outbound heading. This is the simplest and most common entry when your heading is roughly aligned with the inbound course.
• Teardrop entry: You turn to a heading about 30° left of the outbound course, fly for a minute, then turn right to intercept the inbound course. This is used when you approach from the side, such that a direct entry would overshoot the protected area.
• Parallel entry: You track the outbound course (parallel to the holding radial) for a minute, then turn back to the fix. This is used when you approach from the opposite side of the holding pattern.

Common Mistakes and Misconceptions

A frequent mistake is confusing the inbound course with the outbound course. The inbound course is the direction you fly to reach the fix from the holding side; the outbound is the reciprocal. Another error is using magnetic heading instead of true heading—always use magnetic in aviation. Also, the calculator’s teardrop turn angle is simplified; in practice, the turn is 30° left of the outbound heading, not 45°. Always check the published holding pattern for left or right turns; the calculator assumes standard right turns. For left-hand holds, the teardrop turn would be 30° right.

Limitations of the Calculator

This calculator provides a theoretical entry based only on heading and inbound course. It does not account for wind, airspeed, or the exact holding pattern dimensions. In real flight, wind can cause drift, so you must adjust your heading to maintain the proper ground track. Also, the entry type is not the only factor; you must also comply with ATC instructions and published procedures. Use this tool as a planning aid, and always rely on your instrument training and current charts.

Frequently Asked Questions

What is the difference between a holding pattern entry and a holding pattern?

A holding pattern is a racetrack-shaped path flown around a fix, typically used to delay aircraft. The entry is the maneuver you perform to join that racetrack from your current position. The entry type determines how you initially join the pattern to stay within protected airspace.

How do I determine the inbound course for a holding pattern?

The inbound course is the radial or bearing you would fly to reach the holding fix from the outbound side. It is usually published on the approach plate or chart. For example, if the holding pattern is on the 360° radial, the inbound course is 180° (the reciprocal).

Does the calculator work for non-standard holding patterns (left turns)?

No, it assumes a standard right-turn pattern. For left-turn patterns, the teardrop entry would require a right turn instead of left. You can still use the calculator to get the entry type, but the initial turn heading would be different. Adjust accordingly based on the pattern direction.

Why does the calculator show a teardrop entry for a heading of 270° and inbound of 180°?

Because the angle difference is 270°, which falls in the teardrop range (181–270°). In practice, this boundary is sometimes treated as parallel, but the calculator uses a simplified rule. Always verify with your training materials.

Can I use this calculator for planning a real flight?

Yes, but only as a quick reference. It does not replace proper flight planning, which includes wind correction, fuel considerations, and ATC instructions. Always consult current charts and follow your instrument procedures.

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in inbound | Inbound course to fix | deg | 180 | 0
in heading | Current heading | deg | 270 | 0
out entry | Recommended entry | - | if(mod(inbound - heading + 360, 360)