Aircraft use transponder codes to identify themselves to air traffic controllers and, when the need arises, to indicate emergencies, such as squawk 7500.
What are aircraft transponders?
An aircraft transponder is a device installed on the flight deck that responds to interrogation by ground radar stations by transmitting an identification code and altitude or other information.
In the early days of aviation, pilots had to rely on visual cues to navigate their aircraft. This became increasingly difficult as air traffic increased and planes began to fly at higher altitudes. In the 1930s, engineers developed a new type of radar that could track aircraft by bouncing radio waves off of them. This system, known as primary radar, was soon adapted for use in air traffic control. However, it had several limitations. In particular, it didn’t provide any information about the aircraft’s altitude, only its range and bearing.
In the 1950s, engineers came up with a new type of radar system that addressed these limitations. This system, known as secondary surveillance radar (SSR), involves the radar unit sending a signal to the aircraft requesting information (interrogation), and the aircraft uses a transponder to reflect the signal to the radar station. The term transponder refers to the fact that the signal is transmitted and the unit responds.
Today, aircraft transponders are an essential part of air traffic control, and they’ve played a vital role in making flying safer for everyone. As well as being mandatory aboard commercial aircraft they are widely used by general aviation aircraft as well since Mode C transponders have become mandatory in most airspaces.
What does it mean when an aircraft ‘squawks’ a code?
When the pilot of an aircraft makes contact with the air traffic controllers responsible for the airspace through which the aircraft is flying, the ATC will ask the pilot to ‘squawk’ a particular four-digit code.
The pilot complies and sets the code on the transponder in the cockpit. With the code set, ATC may also ask the pilot to ‘Ident‘ button on the transponder by saying, “ident“. Once pressed, this button gives the signal an extra boost and helps ATC to find the particular aircraft on their busy screens.
When the pilot changes radio frequency as it moves into another section of airspace, he or she can inform the air traffic controllers of the code currently in use on the aircraft. They may note that or request that the pilot changes the transponder to another code.
What does squawk 7700 mean?
The squawk code 7700 is a radar emergency code. When activated, it notifies air traffic control of an emergency and that it may need to deviate from its flight plan.
The emergencies that may give rise to the use of this code include things like; bird strikes; a medical emergency onboard the aircraft; engine failure; depressurization; fires in the cabin or cockpit; low fuel; or severe icing that may impede the aircraft’s ability to fly safely, and any other malfunction of essential equipment.
Due to the number of aircraft in the air each day globally, this code can be seen in use several times a day when using for example, and flight tracking app like FlightRadar24. However, the vast majority of these incidents are resolved without injury, death, or damage.
Declaring an emergency gives the pilot in command more options. It allows the air crew to take whatever action they think is necessary and ATC give them the space in which to do so. So by squawking 7700 early on in the emergency situation they can resolve it without anything catastrophic happening.
What does squawk 7600 mean?
The squawk code 7600 is used to inform air traffic control of a radio failure aboard an aircraft. In this situation, the pilot will continue to transmit messages just in case the transmissions are still working even if they cannot hear any replies i.e. the pilot will transmit blind.
The pilot will then land as soon as possible, but only once it has received the appropriate light signal from the ATC tower when it is in sight of the airport.
What does squawk 7500 mean?
The squawk code 7600 is an emergency code meaning “we are being hijacked.” It informs ATC that the aircraft has been taken over by a hijacker or that a plane hijacking or some other unlawful interference is being attempted.
Thankfully, aircraft squawking 7500 are rare but there have been occasions when it was used in earnest when the crew of hijacked aircraft have had time to surreptitiously set this transponder code on the flight deck before the hijackers gained access to the cockpit.
What is ADS-B?
ADS-B is an aviation acronym that stands for Automatic Dependent Surveillance-Broadcast. It is a technology that uses GPS satellites to track aircraft and share their location with ATC and other aircraft in the area. ADS-B has been mandated by the FAA for all aircraft operating in controlled airspace since 2020.
The benefits of ADS-B include increased safety, efficiency, and capacity in the airspace. Additionally, it provides pilots with real-time data on aircraft positions and weather conditions, allowing for more informed decisions about flight paths and altitudes. As a result, ADS-B is transforming the aviation industry and making flying safer for everyone involved.
Radar is a system that uses radio waves to detect objects, such as aircraft, and track their movement. Aircraft transponders are devices that respond to radar signals by transmitting a code comprised of four digits that identifies the aircraft. This code is called a squawk code and it allows for the easy identification of aircraft on ATC screens.
There are four digit codes used for emergency situations, and they can be easily identified by air traffic controllers. In the event of a hijacking, the pilot will usually switch to the emergency squawk code. The local authorities will be notified and will take action.