31 votes
Accepted

Why does secondary surveillance radar use a different antenna design than primary radar?

With the secondary system, you are simply sending a one-way message from the radio tower to the transponder in the plane, and the transponder is transmitting a message back from the plane to the radio ...
Max R's user avatar
  • 3,780
20 votes
Accepted

Identifying WWII reconnaissance plane wing

It looked too short to be a C-47 wing, which meant it was most likely a Beech 18. And sure enough, in the cropped image below (taken from a copyrighted image - uncropped pic at the link above), you ...
John K's user avatar
  • 130k
12 votes

To what extent is modern "maneuverable spy balloonery" really a thing?

To what extent is modern "maneuverable spy balloonery" really a thing? To the extent that it helps to sell news and stoke irrational fear of secret Chinese technology. Much of what a "...
Peter Kämpf's user avatar
12 votes
Accepted

How are aircraft separated in a non-radar environment?

You are asking two very different, but related, questions: How is separation provided in procedural airspace? (that is, airspace where no surveillance exists) What are the emergency procedures when a ...
60levelchange's user avatar
9 votes

How did the USS Vincennes misidentify an Airbus aircraft?

tl;dr We don't know. The US Government has not made enough information available to answer this question. The official Iranian and US reports contradict each other. Inofficial accounts of sailors on ...
Jörg W Mittag's user avatar
9 votes

What aircraft would have these tail numbers?

I'm convinced this numbers were fligtradar-internal identifiers, nothing concerning the flights themselves. The following is not an answer, just what I know about flightradar data records and where to ...
sweber's user avatar
  • 7,257
9 votes
Accepted

Why bits are mixed up (interleaved) during ATC transponder mode A and mode C reply format?

Mode 1 transponders only had six bits: A1, A2, A4, B1, B2 and B4, which clearly wasn’t sufficient to identify specific aircraft. Each day, all pilots would be given a common code to squawk when ...
StephenS's user avatar
  • 27.7k
8 votes
Accepted

Why were these Hawkeyes flying in a circular pattern?

They were most probably training touch-and-go passes. USN conducts carrier landing practice at NASA's Wallops Flight Facility for E-2 Hawkeyes and C-2 Greyhounds. As Lt. Commander Mike Ferrara, an ...
aeroalias's user avatar
  • 100k
8 votes
Accepted

What is the broadcast rate of an ADS-B message?

It depends on the Message Format TYPE Code and the aircraft state. In your example, being on final approach would have no effect as the primary state criteria is being airborne (vs. surface). The ...
Gerry's user avatar
  • 19.7k
7 votes

What aircraft would have these tail numbers?

Aircraft equipped with Mode S transponders transmit a unique 24 bit aircraft ID, in addition to a 4 digit transponder code (squawk). There are two ways of displaying this unique ID, as an 8 digit ...
JScarry's user avatar
  • 7,379
6 votes

Why do we need to enter squawk code when mode-s has ICAO 24-bit address?

Mode S was not introduced because of a shortage of Mode A (squawk) codes in congested airspace, but to improve the radar performance. In congested airspace, a Mode A/C radar suffers from two technical ...
DeltaLima's user avatar
  • 83.1k
5 votes
Accepted

When is squawk 1000 assigned in USA?

Currently, FAA's "fusion" software uses discrete squawk codes to merge targets generated by different surveillance systems, i.e. SSR (often several of them) and ADS-B. They plan to upgrade the ...
StephenS's user avatar
  • 27.7k
5 votes
Accepted

Is a Mode C or S Transponder a type of Mode 3 Transponder?

Modes 3/A and C are very similar, but the interrogation pulses are timed differently and the responses mean different things. If you send a mode 3/A pulse, you get a mode 3/A reply (or nothing). The ...
StephenS's user avatar
  • 27.7k
4 votes

To what extent is modern "maneuverable spy balloonery" really a thing?

to what extent is modern maneuverable spy balloonery really a thing? While it is certainly debatable whether or not recent balloons in the news were maneuverable or not, technology does exist to ...
Robert DiGiovanni's user avatar
4 votes
Accepted

Is RTCA DO-260 Change 1 the same as DO-260A?

DO-260 change 1 is not DO-260A. DO-260A released in April 2003 DO-260A change 1 in June 2006 DO-260A change 2 in December 2006 The releases marked as 'change' contain editorial changes, ...
DeltaLima's user avatar
  • 83.1k
4 votes
Accepted

Why doesn't ADS-B use satcoms like ADS-C?

ADS Broadcast and ADS Contract are intended for different purposes. They use the same type of equipment except for the link technology, which is matched to the differing intent. ADSB is intended to ...
Pilothead's user avatar
  • 20k
4 votes
Accepted

What aircraft would have these tail numbers?

The two aircraft in question were actually only one. Apparently it was a glitch in the FR24 system. It was an Embraer ERJ-190AR, registration number N949UW on flight AA1678 from ATL to LGA. This ...
TomMcW's user avatar
  • 28.4k
3 votes

When is squawk 1000 assigned in USA?

1000 is a blockout code that prevents the ADS-B transmitter from also sending its discrete code, if you enter 1000 on your transponder no Mode 3/A code is sent in the ADS-B OUT message. Its part of AC-...
Dave's user avatar
  • 101k
2 votes

When will the Canadian ADS-B satellite system be implemented?

Just to clarify something to start, NAV CANADA is not a majority shareholder in Iridium Communications Inc., but rather Aireon LLC (the provider of space-based ADS-B service). The Aireon payload is a "...
chatty's user avatar
  • 1,757
2 votes

When will the Canadian ADS-B satellite system be implemented?

This Advisory Circular, although from 2011, is still current and indicates that there will no Transport Canada ADSB mandate (being regulatory, it's not up to Nav Canada). It appears the policy is to ...
John K's user avatar
  • 130k
2 votes

What were DJI drones spying on? What data did they capture?

I doubt anything was gleaned per se, but there was recognized a significant security risk here and the military discontinued the use of the produce for fear of integral malware which could give an ...
Romeo_4808N's user avatar
  • 73.5k
2 votes

According to which rule, the maritime patrol aircraft are categorized?

As a military aircraft, they are regulated under FAA Chapter "get outta here, civilian, or I'll call Shore Patrol and have you arrested for trespassing". In other words, it's military, so ...
Harper - Reinstate Monica's user avatar
2 votes

To what extent is modern "maneuverable spy balloonery" really a thing?

For intelligence gathering a balloon would have a couple of advantages and several disadvantages. The disadvantages first. Limited maneuverability, most balloons can only float on the wind. You could ...
Jim's user avatar
  • 951
1 vote

What frequencies are used to transmit ADS-B messages?

1090 MHz Mode S Extended Squitter. This is broadcast on 1090 MHz. It is a capability embedded in virtually all current Mode S transponders. The transponders also support Enhanced Surveillance which ...
Gerry's user avatar
  • 19.7k
1 vote

Why do we need to enter squawk code when mode-s has ICAO 24-bit address?

In some countries, if the equipment codes in the flight plan indicate mode S capability, the computer will assign a squawk code of 1000, which is a special code that causes the transponder to not ...
StephenS's user avatar
  • 27.7k
1 vote

Is a Mode C or S Transponder a type of Mode 3 Transponder?

In simplistic terms you can view Mode S as an "enhancement" of the Mode 3/C/A. Mode S changed the way transponders were interrogated by allowing the radar to interrogate one target at a time. This ...
DLH's user avatar
  • 5,789

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