ER-2 Flight Operations
While there is considerable variety in missions and campaigns, some standard practices have emerged. The following outline is how the majority of ER-2 missions are conducted.
The ground crew, pilots, and investigators meet three hours before the scheduled take off time, usually set the day before. At this meeting, available weather information is reviewed, the investigators brief the pilots on the desired mission objectives, and the status of the aircraft and its instruments is reviewed. If the weather permits, and the investigators feel that there is a reasonable chance of meeting their science objectives, the preparation for a flight begins. Each instrument team, and the aircraft ground crew, begins their pre-flight inspections and preparations, while the aircraft is still inside the hangar. Aircraft systems and instruments are tested, and the ejection seat and related life support hardware are installed in the cockpit.
Approximately two hours prior to flight the aircraft is towed from the hangar and fueled. During this operation, no electrical power will be available to the aircraft. For safety reasons, personnel whose tasks are not connected with this operation will not be allowed near the aircraft at this time. When fueling and oxygen replenishment are completed, external power will be connected to the aircraft (approximately one hour prior to launch). In order to prevent possible damage from voltage transients, the instruments will normally be shut off while external power is removed and internal power is selected. If continuous power is necessary for a particular instrument, arrangements must be made well in advance.
About one hour prior to flight, the mission pilot suits up and begins pre-breathing pure oxygen, to purge nitrogen from his bloodstream. Since the pressure suit worn by the mission pilot restricts mobility and makes pre-flight checks difficult, the mobile pilot inspects the aircraft approximately one hour prior to launch. With the pre-flight checks completed, the mission pilot will be driven to the aircraft in a support van approximately 30 minutes prior to scheduled launch.
The engine is started approximately fifteen minutes prior to launch. Once the pilot is disconnected from the ground oxygen supply, and the canopy is closed, heat will build rapidly in the pilot's pressure suit. For this reason the aircraft is taxied to the runway as soon as possible following post engine start-up checks.
Taxi & Takeoff
The ER-2's long, flexible wings are supported during ground taxi and takeoff by auxiliary wheels, called "pogos". These wheels, as well as the main gear, are locked in place during taxi. The mobile pilot and the ground crew accompanies the aircraft to the active runway in a van or jeep. This vehicle is equipped with radios to talk to both the airfield tower operators and the ER-2 pilot. Once the ER-2 has taxied onto the active runway in position for launch, the ground crew pulls the locking pins for the pogos and main gear. During the takeoff roll, when the ER-2's wings develop enough lift to flex upward, the pogos drop to the runway below. The ground crew recovers the pogos and returns to the hangar. The pogos can usually be used hundreds of times before needing to be replaced, although they must be carefully inspected for damage after each takeoff.
To minimize the impact of the ER-2's flight profile on Air Traffic Control, the ER-2 strives to launch on time. A limited amount of time (30 seconds) is available prior to launch to turn on instruments. The first twenty-five minutes of flight are usually the busiest, and little time is left to manipulate instruments.
High Altitude Operations
The desired altitude and range must be within the performance limitations of the aircraft. Other restrictions may be imposed due to turbulence, winds at altitude, temperature, or lack of visible horizon for attitude reference in the event of emergency. The pilot can decide whether the mission will be continued, if these or other conditions become a matter of concern.
The mobile pilot back at the launch site maintains radio contact with the mission pilot to the greatest extent possible. However, communication is limited to mission-essential information.
Descent & Landing
When the mission has been completed, descent from high altitude is begun. The pilot throttles the engine back, deploys the speed brakes, flaps, and spoilers, and drops the landing gear to aid his descent. This is generally begun a half hour prior to landing and results in a nominal descent rate of about 2000 feet/minute.
The aircraft is always chilled from its visit to the stratosphere, and upon returning to the moister air of the troposphere, condensation inevitably forms. This can be more than an annoyance for sensitive instruments.
Normally, instruments are turned off before beginning descent or just prior to landing, depending on investigator preference. However, instruments can also remain powered for a short time after landing for sensor calibration. As is the case in pre-flight procedures, the pilot may be subjected to overheating, once the outside air warms up and the engine is no longer at a high enough power setting to cool the suit. For this reason only thirty seconds to a minute are used for post-landing, power-on sensor checks.
The ER-2 lands on its main (center) gear and tail wheel, without its pogos to stabilize it. The pilot balances the aircraft like a bicycle until he slows to a stop on the runway. The ground crew, in the launch and recovery vehicle, are waiting on the runway to re-insert the pogos into the wings, and lock all the landing gear into position. Then the ER-2 and its support vehicle taxi back to the hangar.
Post Flight Shutdown
After engine shutdown, the ground crew installs safeties on critical items and disconnects the pilot from the myriad of connections to the cockpit. The pilot normally gives a brief summary of the mission and aircraft status to the crew chief before returning to the life support staging area to remove his suit. A more extensive debrief to the investigators, if requested, usually follows fifteen to thirty minutes later.
Due to the time required for aircraft gyros to wind down, and normal maintenance procedures to be conducted, investigators should allow for thirty minutes to one hour after engine shutdown before instruments can be accessed.
Operating LimitationsGeneral Considerations
The guidelines for ER-2 operations are based upon more than 40 years of Air Force and NASA experience in this type aircraft, current FAA rules and regulations, medical opinions and directives, real time safety assessments, common sense and fiscal realities. By design there are three firm rules:
Flight Frequency & Schedules
Normally, flights can be repeated day after day, as long as the total duty day follows the restrictions outlined above.
At 1300 hours (local time) on the day prior to each planned flight, a decision will be made on the mission possibilities for the next day. Flight plan options are presented and maintenance crew report times are set based on the earliest possible launch time. After this decision only limited changes which delay the launch time will be considered. No changes will be considered after three hours prior to scheduled launch time. If changes are mandatory within this time frame, the flight will be delayed or canceled as appropriate.
The special nature of the ER-2 landing gear limits the aircraft to operations where wind speed, or projected wind speed, in any direction, is less than 30 knots. In addition, cross winds of 15 knots will cause flight operations to cease. Snow and ice present special problems for the ER-2 landing gear. No takeoffs or landings will be attempted in snow or icy conditions.
Operations Over Remote Terrain
A limited amount of survival gear is packed into the pilots seat. This will not protect the pilot for extended periods of time in severely inhospitable regions. For this reason, the scientific justification for the flight must be weighed against the danger to the pilot in the event of a mishap. The ER-2 operations staff will make the ultimate decision as to whether such flights will be undertaken.