A primary flight instrument for the shuttle pilots was the Attitude Direction Indicator (ADI). In the STS-51L days this was a electromechanical instrument, indicated in the photo by the red arrow.
The frame of reference used to drive the display is determined by the ADI ATTITUDE switch. Its function is as follows:
The ADI ATTITUDE switches determine the unit’s frame of reference:
INRTL (inertial), LVLH (local vertical/local horizontal), and REF
(reference). The INRTL position allows the flight crew to view the
orbiter’s attitude with respect to the inertial reference frame.
The LVLH position shows the orbiter’s attitude from an orbiter-centered
rotating reference frame with respect to Earth. The REF position is
primarily used to see the orbiter’s attitude with respect to an
inertial reference frame defined when the flight crew last depressed
the ATT REF pushbutton above/below the ADI ATTITUDE switch. The REF
position is useful when the crew flies back to a previous attitude or
monitors an OMS burn for attitude excursions. On ascent pre-MECO and
on entry, with the ADI in LVLH, yaw is not displayed and the ADI is
pinned to the belly-band in yaw.
Pre-launch, the ADI ATTITUDE switch is set to the REF position, although LVLH is the desired frame of reference for flying the Orbiter in "airplane mode". This means that shortly after liftoff, the switch must be moved to LVLH to set up the instrument for a possible ascent abort. Although it was desirable to avoid switch throws during ascent, the switch could not be pre-positioned to LVLH by the Astronaut Support Personnel (ASPs, or "Cape Crusaders") who set the cockpit switches, because there was a singularity in the calculations of LVLH attitude at pitch of 90 degrees (which the Orbiter was at on the pad).
This image shows the layout of the ADI switches in the "steam gauge" cockpit. The location of the switches is outlined in green in the drawing and the photo.
The first action taken after liftoff is, therefore, movement of this switch, as seen on the Ascent Checklist Ascent Procedures Cue Card. The "R180" in the checklist indicates that the action should be taken after the roll maneuver which orients the shuttle to its launch azimuth is complete, resulting in a displayed roll attitude of 180 on the ADI. (These cue cards would have been velcroed to the cockpit in front of the commander and pilot as part of the Ascent Flip Book; you can see a Flip Book velcroed on in the picture. Resnik would have had copies of these cue cards in her copy of the Ascent Checklist.)
Resnik was reading these steps to the commander and pilot because her flight assignment for the launch of STS-51L was Mission Specialist-2 (MS-2). This means that she served as the "flight engineer", responsible for keeping up in the checklists and ensuring that the commander and pilot took the appropriate actions. She was seated in the second row of seats on the flight deck, between the pilot and commander, giving her a good view of the onboard computer displays and the two crewmembers in front.
- personal photo from the Shuttle Mission Simulator
- hardcopy of STS-86 ascent checklist cue card
- Shuttle Crew Operations Manual (Various, but page 2.7-4 and 7.1-4 mainly)
- Old cockpit graphic from here