Catacombs Model Gallery
Eagle viewscreen

All the panels are real aircraft instruments. They are life-sized photos cut from aircraft instrument catalogues. The catalogues are from Sperry Flight Systems (now Honeywell Aerospace), King Radio (now Bendix/King by Honeywell) and Narco Avionics. They are state of the art 1970s-era analogue controls. Most are still in use today, and are little changed, but since the 1990s aircraft controls have increasing moved to LCD screens (so called "glass cockpits").

The Eagle has many duplicate instruments. This is not unrealistic for some of them. The numerous heading indicators are wildly contradictory (some say the craft is flying North, some South, some South-East; one altimeter says the craft is on the ground, the other says it is at 12700 feet). It is lacking some common instruments, including any vertical speed indicator (VSI).

Top right is the "TOR transponder". A transponder is a Transmitter-responder, often a device that receives a signal and transmits an automatic response. All aircraft have transponders which are used by air traffic secondary radar - it sends an interrogation signal, and the aircraft transponder receives it and replies with the aircraft identification or altitude.

It actually includes a Narco DME 190, which is, in reality, a transponder. This DME (Distance Measuring Equipment) is tuned to receive on 115.70Mhz and transmit on 110.60Mhz (you can see the frequencies on the panel). All aircraft have a 4 digit octal number transponder code - this Eagle's identification is "1200", at the bottom of the panel. The mode switch alongside the code is set to "ALT"- which responds to identification and altitude secondary radar signals- the other modes (Off, Test, Standby) should obviously not be used in flight, although On may be used when (barometric) altitude signals are unreliable. The "IDENT" button above sends a "squawk" pulse in the signal, so the traffic controller sees the signal flash on his screen. At the top the DME shows the exact position from a ground station which is 23.2 miles (you can also set to show minutes or knots). The Narco DME 190, introduced in 1975, was the first totally solid state DME, and is still in use today.

The King Course Deviation Indicator (CDI) alongside the DME is set with 360 degrees (North) at the primary index, the needle is centred and the To/From indicator is showing "TO". The radial is indicating that the aircraft is on the 360 degree course (North) to the ground station (this means the aircraft is South of the ground station).

At the bottom under the viewscreen is the NAV. DME panel. The dial is a horizontal situation indicator (HSI), an instrument that combines a directional gyro (DG) and a Course Deviation Indicator (CDI). Note the aircraft symbol in the centre, and unlike the other CDIs this one is heading South according to the compass rose. Note the course selector is set to 210 degrees, a little to the west of where we're going. Below it is a Sperry Stars Flight Director (Stars stands for Sperry Three Axis Reference system) computer controller. The first auto-pilots, enabling a pilot to set the plane to fly straight ahead without touching the controls, were invented by Sperry in 1912, and in the 1960s the Sperry Stars flight directors introduced computer control to aircraft.

Bottom right under the viewscreen is this "VOR display / Readout" panel. The absolute altitude dial under the "Readout" label shows 1300ft (396m). The "VOR display" is actually a DME (Distance Measuring Equipment) rather than a VOR (VHF omnidirectional radio range beacon). It shows 50 miles to the DME ground station (which will probably also be a VOR beacon). The craft is travelling at 283 knots (146 metres per second). The DME is set to RTS mode (Request to Send) rather than TTS (Time to Station). At the bottom a Narco AT-50A Transponder shows the Eagle's ident to be 1200 (the same as the Narco DME 190 on the "TOR Responder" panel on the top right of the viewscreen panel).

Also under the viewscreen is a panel marked with the Letraset title "Glideslope". A glideslope or glidepath (GP) antenna array is sited to one side of the runway and together with the localizer antenna array it provides information for the instrument landing system (ILS). This is displayed on a nav indicator such as the HSI and the attitude indicators that appear in the panel, helping the pilot to approach the runway on the correct course and rate of descent.

These instruments are on the lower left of the viewscreen. "Computer gravity analysis" has a CDI set to 330 degrees, North-North-West, and a small radar altimeter showing 0 height. The red and white chevrons are marked "Walkway Forward" and most strange is the small red triangle "Ejection Seat" with "Danger" written on each side.

The panel below shows odd Letraset writing too: "Location for Wing Tip ---- Steadying trestle". This is a mark found on the exterior of an aircraft, showing where to place a supporting frame. It's likely this is Letraset marking from a model kit, perhaps a Submarine Spitfire which has this wording. The largest instruments is a King KDM 705A DME, showing speed- time to station (SPD-TTS) at 339, and distance at 112.5 miles.

On the bottom left is this panel, marked with the simple word "BOGUS", plus small text reading "Fuel DTD 230 Capacity 85 Gals". DTD 230 is the British Air Ministry "Director of Technical Development" specification 230, published in 1936, that specified 86 octane petrol. The capacity of 86 gallons (325.5 litres) is equivalent to a small Piper PA-32 Cherokee Six light aircraft.