ER-2 On-Board Aircraft Systems
Radio Navigation and Communications Systems
The ER-2 is equipped with UHF, VHF, and HF radio systems for two-way voice communication. An Air Traffic Control (ATC) transponder enables surveillance radar to identify the aircraft via coded transmissions.
The ER-2 can navigate with respect to ground based radio beacons, as selected by the pilot. Navigation aids used for this include: low-frequency Automatic Direction Finding (ADF), Tactical Air Navigation (TACAN) for bearing and range information, and a VHF Omnidirectional Range/Instrument Landing System (VOR/ILS).
Inertial Navigation Systems
The Inertial Navigation System (INS) on the ER-2 operates by sensing accelerations from a gyro-stabilized, all-attitude platform. This information is integrated by a digital computer to provide an indication of present position (latitude and longitude), attitude data (pitch and roll), and course line computation referenced to great circle routes. A control display unit in the cockpit allows the pilot to store navigation way points and to change the flight track enroute. A self-contained system, the INS offers world-wide navigation capability.
An update function allows for GPS updating of the INS to provide navigation independent of the drift errors. GPS accuracy is better than +/-100 meters depending upon satellite orbit geometry.
Optical View Sight
The optical view sight offers the pilot visual coverage of the terrain underneath the aircraft for navigation purposes. The pilot may select a viewing angle of up to 70 degree with respect to nadir in any direction. Extra elevation is available for horizon viewing in the extreme forward and aft scanning positions. A field of view of 15 degree or 37 degree is available in the 1X and 0.4X magnification settings.
The ER-2 navigation data recorder is an electronic intermediary between aircraft avionics and experimenter hardware. The recorder performs the following functions:
- Opto-isolates experimenter hardware from aircraft avionics.
- Broadcasts navigation data parameters in-flight to all payload areas. These parameters include the aircraft's attitude, position, velocity, heading, outside air temperature and pressure, etc.
- Broadcasts a consistent time base to all payload areas, in both IRIG-B time code format and an RS-232 serial line.
- Samples and records a variety of general analog and digital inputs.
- Stores navigation data for post-flight analysis, dissemination, and archival.
The navigation recorder is a custom-built 486-class computer with a removable hard drive. Stored data is usually available to investigators post-flight within an hour after the plane lands.