Questions tagged [radar]

Radar is a surveillance technology that uses radio waves to determine the range (and azimuth) of an aircraft. It works by measuring the time difference between a radio transmission and the echo or reply to that transmission. Radars are the most common surveillance equipment used by ATC.

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Can someone actually "fly under the radar"?

It is quite a common phrase, usually without having anything to do with radar or aviation. But. Is there such a thing as 'flying under the radar'? If so, why is this (and how low is that)?
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How is a missile lock detected?

How can a fighter aircraft involved in a face-off detect a missile lock from a trailing aircraft so that it can make evasive maneuvers?
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Why do pilots have the ability to turn off the transponder in-flight?

These days, when reading news about missing Malaysia Airlines Boeing 777-200, I keep coming across a scenario where pilot might have deliberately turned off the transponder which is used for the ...
SRy's user avatar
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Would a homemade lawn chair balloon be visible on ATC and collision avoidance radar?

I am not a pilot, but have a question about radar detection of improvised lawn chair balloons that I thought might be on-topic here. This BBC news article describes a marketing stunt gone awry ...
Paul's user avatar
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37 votes
1 answer
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Why does a radar altimeter show negative values on the ground?

This applies to the Airbus 320 or Boeing 737, among others: Although it is useless on ground, the radar altimeter will repeatedly display a value (including negative) for a specific runway and airport ...
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30 votes
3 answers
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What is this radar-like thing?

A friend of mine sent me this picture, which Is somewhere in Miami. But I don't seem to recognize it
user22659's user avatar
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29 votes
5 answers
10k views

How is radar used to help aiming a gun on fighter jets?

I know gatling gun is fixed mounted to the airframe of the plane, thus cannot be rotated left/ right or up/down. However watching DCS pilots dogfighting with opponents they sometimes mention their ...
svizko's user avatar
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29 votes
4 answers
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Can a helicopter mask itself from radar?

I have read somewhere that if a helicopter is traveling under 100 km/h and below 5 meters AGL then most radars will ignore it. From what I understand of this process, the radars can pick up things ...
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28 votes
6 answers
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Is it possible for a modern commercial airliner to stop being tracked without substantial mechanical failure?

I was speaking to someone about the MH370 incident, and they suggested that a hijacker could turn off the device that sends the plane's current position, resulting in the appearance of a catastrophic ...
andrewb's user avatar
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25 votes
7 answers
9k views

Which map projection is typically used on ATC radar screens?

Displaying a (roughly) spherical surface on a flat map turns out to be pretty difficult. There are many different map projections, each with their advantages and disadvantages. Some of the most common ...
60levelchange's user avatar
22 votes
4 answers
7k views

Could an aircraft 'hide' in the aircraft shadow of another aircraft without being detected or noticed?

I just finished reading an interesting post where the author suggests that the missing Malaysian Airlines flight 370 could have 'hidden' under the cover of Singapore Airlines flight 68 to fly to a ...
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1 answer
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How does ATC radar/ADS-B ground stations not get confused with signals sent from multiple aircraft?

I understand that the radar sends a 1030 MHz interrogation signal to an aircraft and the aircraft's transpoder responds using 1090 MHz. When it comes to Mode S squitter, the transmissions are ...
Clive's user avatar
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How does IFF work?

How does Identification Friend or Foe (IFF) work? Are radar images of friendly planes recorded, or do friendly planes have transponders on them?
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How did pilots avoid thunderstorms and related weather before “reliable” airborne weather radar was introduced on airliners?

How did airline and or mail pilots avoid hazardous weather especially at night before airborne weather radar systems were in use?
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How can a single misplaced screw so massively increase a stealth aircraft's radar cross-section?

In this comment on one of the answers to an earlier question of mine, @CarloFelicione points out how even the tiniest of imperfections can make a stealth aircraft much more visible to radar: A ...
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20 votes
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How did the gyro gunsights of WW2 get the range and lead of a target?

I just read this article on the gyro gunsight, but I don't understand how it computed range/position to the target and then calculated how much lead is needed. Surely it must have had radar to get ...
DrZ214's user avatar
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How are aircraft separated in a non-radar environment?

In remote areas that have no radar (oceanic airspace, etc.) how is aircraft separation maintained so that airplanes don't get too close? What do areas that normally have radar do when there is a ...
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How does the weather radar work?

I was reading this question about turbulence and how pilots foresee it, and in one of the answers, @Rhino Driver states: Weather Radar Just like using your eyes, except the radar can see further ...
Gabriel Brito's user avatar
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1 answer
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Is Doppler navigation still in use for civilian aircraft?

Is it possible to find an airliner nowadays with Doppler radar used for navigation purposes?
Andrea Ghilardi's user avatar
19 votes
2 answers
16k views

What data is displayed on civilian ATC radar screens?

I am developping an ATC radar for a simulation. I don't think there is any standard for radars to show aircraft data on radar screens. But there should be general data to show on radar screens. For ...
Muzaffer Karaman's user avatar
18 votes
2 answers
3k views

Why does the radar dome on the E-3 have a white stripe down the middle?

Every picture I can find of the Boeing E-3 Sentry has a blue/black radar dome on top with a fairly thick white stripe down the middle but I can't figure out why. Is it perhaps related to the position ...
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What is that airport equipment that looks like an SMR but rotates like a windmill?

— YouTube The one rotating horizontally looks like a standard Surface Movement Radar (SMR). But the one next it, rotating vertically (like a windmill or wind turbine), what is that? Wouldn't that be ...
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17 votes
7 answers
4k views

Why do (or did, until very recently) aircraft transponders wait to be interrogated before broadcasting beacon signals?

An aircraft’s transponder transmits signals that announce (at the very least) the aircraft’s identity, altitude, and direction of motion (plus, for most newer aircraft, a whole slew of other useful ...
Vikki's user avatar
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17 votes
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Does the F-22 (or any other stealth aircraft) carry chaff?

Considering it is nearly undetectable on radar, it seems like it wouldn't have to worry about radar guided missiles; in addition to this it is sure to have sophisticated jamming capabilities. So why ...
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16 votes
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Does a secondary surveillance radar need the support of a primary surveillance radar?

ATC technologies are evolving to include other components than primary and secondary surveillance radars, but I believe these two pieces of equipment are still the backbone of ATC. Primary radar (PSR, ...
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Do military jets' radar jammers block their own radar? And, if not, why not?

Will a noise jammer block the fighter's own radar? If I have understood it, a noise jammer, e.g., a barrage jammer, will emit a noise signal across a wide frequency band. Won't this make it hard to ...
user16077's user avatar
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16 votes
3 answers
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What is the range and accuracy of ATC radar systems?

What is the average range, accuracy, and update frequency of radar systems used to monitor airspace in the USA? I'm primarily interested in capabilities for tracking smaller general aviation aircraft ...
kaliatech's user avatar
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15 votes
5 answers
4k views

What is the significance of radar cross section (RCS) for air defense?

From the internet or any other medium of information I came to know that some cutting edge stealth aircraft have radar cross sections of a bird (or something similarly small). I don't have the in ...
lousycoder's user avatar
14 votes
4 answers
21k views

Where can I find real-time flight tracking with the least amount of delay?

I am an aviation fan, relatively new to the industry. While I thoroughly enjoy plane spotting at my local KORD airport, at times I tune to LiveATC and Flightaware to get my fix. Unfortunately, my ...
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14 votes
2 answers
808 views

How does a runway inspection radar work?

In AC 150/5220-24 FAA mentions radar equipment to detect foreign object debris (FOD) on runways, based on stationary and mobile radars with an astronomical precision, e.g. able to detect an object as ...
mins's user avatar
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13 votes
2 answers
3k views

How does a PESA radar work?

I have been trying to understand how a PESA radar works. Essentially, it uses one signal that is electronically delayed. How is the reception coordinated and known by the receiver? I am interested in ...
Trebia Project.'s user avatar
13 votes
2 answers
7k views

Why is the AWACS' rotodome located at the back and over the aircraft?

Browsing this website, I found this question dealing with torque due to the huge piece in motion, and its answers also speak of drag. The rotodome is located above the aircraft and at the aft of the ...
Manu H's user avatar
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13 votes
3 answers
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Why aren't bird radars placed on the front of commercial aircraft?

Unfortunately, my skills and understanding of radar and the like are very limited, but if somebody could enlighten me why there is no such thing as a dual bird/weather radar to switch to? I've ...
Thunderstrike's user avatar
13 votes
2 answers
1k views

Is "secondary radar" a misnomer?

Radar is based on the principle of transmitting radio waves and measuring the length of time-of-flight, direction, and frequency shift of the returning reflections or echoes. In aviation, we call ...
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12 votes
2 answers
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Did the Stuka Ju-87 really have a radio altimeter? If so, when?

This is what Wikipedia says near the end of its radio altimeter article: The radio altimeter first showed up in the German Junkers Ju-87 "Stuka" dive bomber which was equipped with one for ...
DrZ214's user avatar
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12 votes
2 answers
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Did British aircraft fly at a specific speed while returning from missions during WWII?

I remember reading a whole lot ago (so I am currently unable to find the reference, sorry) that during WWII, British aircraft would return from missions at a specific speed that was unattainable from ...
Federico's user avatar
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12 votes
2 answers
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Is the weather radar on and active during the whole flight?

The title says it all: Do airline pilots leave the aircraft's weather radar on at all times during the flight and display the data on one or both of the Navigation Displays, or only if clouds/ weather ...
Stefan's user avatar
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11 votes
1 answer
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Why does secondary surveillance radar use a different antenna design than primary radar?

In radar surveillance we use primary and secondary surveillance radar for different purposes. I'm wondering about the antenna that use in both system: Secondary Radar uses an array antenna Primary ...
Uniform's user avatar
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11 votes
2 answers
4k views

Did WWII fighters do a roll before engaging to identify themselves to radar operators?

There's some folklore in the radar world about the Nazi fighters doing a roll before engagement to mark them to a German radar operator. This makes a lot of sense because it allows you to change your ...
b degnan's user avatar
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11 votes
5 answers
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How is radar separation assured between primary and secondary targets?

Air traffic control radars come in two flavours, with most ATC centers using both and displaying the output of both on a single screen: Primary surveillance radar (PSR) is a true radar system, which ...
Vikki's user avatar
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11 votes
5 answers
1k views

Is it possible for ATC to see who’s transmitting on the radio on their radar?

I don’t think ATC currently has the capability of seeing who’s actually transmitting on the frequency. If technology permits (probably by making a connection between the radios and the transponder), ...
RaajTram's user avatar
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11 votes
1 answer
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Can doppler radar be used to detect stealth aircraft by focusing on the characteristic flow field instead of the aircraft itself?

Any aircraft traversing through the air would impart velocity, pressure, and temperature gradients to the surrounding air, then there are some phenomenon which are unique to all winged bodies such as ...
Tony Stark's user avatar
10 votes
5 answers
5k views

Why does the radome on the AWACS rotate?

I'm not sure I understand why the radome on the AWACS aircraft is so large, and could somebody explain the design and why it has to rotate?
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10 votes
1 answer
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Do airliners have an "anti-pilot" warning system?

In February 2014 a co-pilot hijacked Ethopian Airlines flight 702 and took it to Switzerland. Now in March there is some speculation that Malaysia Airlines flight 370 may have been hijacked and ...
Registered User's user avatar
10 votes
2 answers
4k views

How do ATC radars know where to position a primary target?

Primary target: An aircraft not reporting mode-C, the only thing the controller has is the return on the radar. When a controller reports a primary target as traffic to other aircraft, the controller ...
Yos233's user avatar
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10 votes
2 answers
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How does the F-22 Raptor radar reflector work?

The F-22 Raptor (and other stealth aircraft) can be made more visible to radar by using radar reflectors, or in other words, radar cross section (RCS) enhancers. In the comments section of this answer ...
Jpe61's user avatar
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10 votes
2 answers
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Does huge rotating AWACS radar affect flight characteristics?

I would think that having a huge mass spinning around should produce massive gyroscopic forces when turning or pitching. There must be some clever way of minimising or eliminating the effects... How ...
DefenestrationDay's user avatar
10 votes
1 answer
1k views

How will radar systems be used in FAA's NextGen ATC plans?

Based on the reading I've been doing of FAA's Next Generation Air Traffic Control (NextGen) plans, I've been wondering if and how radar systems will continue to be used for ATC as NextGen rolls out? ...
kaliatech's user avatar
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9 votes
2 answers
1k views

Why didn't the U-2 spyplane have any chaff?

The U-2 spyplane was shot down over Russia in 1960 and over Cuba in 1962, both times by a radar-tracking missile. Why wasn't it equipped with any chaff to throw off the missile? Chaff is just a cloud ...
DrZ214's user avatar
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9 votes
4 answers
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Where is the airspace not covered by primary Radar?

Most ATC in the world rely primarily on secondary radar to know where planes are. This requires that the transponder on the plane works correctly. This means that maintenance and deployment of ...
ratchet freak's user avatar