---
title: "Define flying height"
subject: "Surveying II"
chapter: 7
key: "semester_4/surveying_ii:define-flying-height"
source: https://www.bctengineer.com/q/semester_4/surveying_ii/define-flying-height
site: BCT Engineering
---

# Define flying height

Surveying II · Chapter 7: Photogrammetry and Remote Sensing

- Asked in: 2069 Bhadra, 1 marks
- Video: [Pg Lect13 Importance of flying height, Air base computation](https://www.youtube.com/watch?v=Hn318QS1jJA) — Photogrammetry World
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/surveying_ii/define-flying-height
- Whole chapter: https://www.bctengineer.com/md/semester_4/surveying_ii/chapter-7

## Question

Define flying height.

## Short answer

Vertical distance of the camera lens at exposure above a datum, often mean sea level or average ground level. It controls photo scale: S = f/H above ground.

## Answer

**Flying height** is the vertical distance of the aircraft (the camera lens at the moment of exposure) above a given datum, usually mean sea level, or above the average ground level. For flat ground at elevation $h$ above datum, the photo scale is $S = f/(H - h)$ (or simply $S = f/H$ when $H$ is measured above the ground), so for a given camera a greater flying height gives a smaller scale.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Flying height is the vertical distance of the lens above:
   A. The tallest building
   B. The runway
   C. A given datum, usually mean sea level, or average ground
   D. The photo plane
   Answer: C. It is measured at exposure. (Key point: Definition)

2. For a given camera, greater flying height gives:
   A. Smaller scale
   B. Larger scale
   C. Same scale
   D. Zero scale
   Answer: A. S = f/H decreases as H increases. (Key point: Scale effect)

3. Flat ground scale:
   A. S = H/f
   B. S = fH
   C. S = f/H
   D. S = f-H
   Answer: C. On flat ground at datum, S = f/H. (Key point: Flat ground scale)

## Related in Surveying II

- [Flying height from photo and map scale](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Aflying-height-pq-20cm-focal-24) — Surveying II, chapter 7