How far away is a plane in the sky?

  • Context: High School 
  • Thread starter Thread starter Johndigger
  • Start date Start date
  • Tags Tags
    Plane Sky
Click For Summary

Discussion Overview

The discussion revolves around estimating the distance to a plane in the sky without directly measuring angles. Participants explore methods and considerations related to this estimation, including the use of similar triangles and practical measurement challenges.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether it is possible to determine the distance to a plane without knowing the angles involved.
  • Another participant provides information about typical cruising altitudes for airliners, suggesting a range of 30,000 to 40,000 feet.
  • One participant suggests applying the rule of similar triangles as a potential method for estimation.
  • Another participant challenges the practicality of the measurement method used, arguing that it could lead to significant errors, potentially an order of magnitude off, while acknowledging that similar triangles would be the method in an ideal scenario.

Areas of Agreement / Disagreement

Participants express differing views on the practicality and accuracy of using similar triangles for this estimation, indicating that the discussion remains unresolved regarding the effectiveness of the proposed methods.

Contextual Notes

Limitations include the reliance on the accuracy of the measurement method and the assumptions made about the plane's size and altitude.

Johndigger
Messages
1
Reaction score
0
Ok, my brother & I were trying to work this out.

Without directly knowing the angles is it possible to work out how far away a plane is in the sky?

For example, a boeing 747 is about 70m long. It appeared to be about 0.001m holding out a ruler about 80cm from my eye.


I look forward to reading your replies.

Thank you.
 
Physics news on Phys.org
Welcome to PF.

Airliners at cruise are flying at an altitude between 30,000 feet and 40,000 feet 90% of the time.
 
Apply the rule of similar triangles.
 
As a purely practical thing, the mesurement method used makes any answer he's going to get from similar triangles meaningless. The error is likely to be an order of magnitude out. (at least)

But yeah, in a textbook case, similar triangles is the method.
 

Similar threads

Undergrad Aviation safety plane crash question/idea
  • · Replies 18 ·
Replies
18
Views
2K
High School What Could Explain the Mysterious Red Pulsing Light in the Sky?
  • · Replies 13 ·
Replies
13
Views
5K
Undergrad A busy and interesting night sky in Mackinaw City
  • · Replies 1 ·
Replies
1
Views
2K
High School Star like object travels in a zigzagging pattern relative to other stars
  • · Replies 49 ·
2
Replies
49
Views
12K
High School Audio frequency of a humidifier
  • · Replies 12 ·
Replies
12
Views
1K
High School Strange object in the sky blinking
  • · Replies 3 ·
Replies
3
Views
9K
High School How to draw a plane intersecting a cylinder at a "compound angle"
  • · Replies 8 ·
Replies
8
Views
3K
High School Can someone please identify what I saw? (lights in the night sky)
  • · Replies 25 ·
Replies
25
Views
5K
High School So what's your go-to method to locate M31 (Andromeda Galaxy)?
  • · Replies 13 ·
Replies
13
Views
4K
High School How would light work on a mirror very far away?
  • · Replies 11 ·
Replies
11
Views
2K