AUTOMATIC FLIGHT

The glareshield panel, commonly referred to as the MCP, contains not only the Mode Control Panel, but also the master caution lights & annunciations, fire warning lights and, on the NG's, the EFIS control panels. Whilst the MCP has evolved with the autopilot, the master caution and fire warning lights have remained unchanged through to the present day which is testimony to its good initial design.

707 The original purpose of the glareshield panel was to put the most important warning lights in the most attention grabbing place. The glareshield panel is the only thing at eye level, so the fire panel was put there. (Photo: Paolo DeAngelis, Munich)

727-200adv These 727-200 Adv panels start to combine the fire panel from the 707 with the automatic systems of the early 737's. From left to right you have a rudimentary master caution system (above) or cargo fire (below); autothrottle (above); flight director and fire panel. In the later production 727's the fire switches were moved down to the centre console leaving more room for autopilot & flight director panels and the glareshield panel became identical to the 737-200. (Photo: Mike Olson, Airliners.net)

737-100/200

The 737 saw the fire panel relegated to the throttle quadrant to allow space for the master caution, flight director and autopilot controls. This was the original MCP as fitted to the -100/-200's with the Sperry SP-77 autopilot. They comprised three panels, the autopilot (centre) and one for each flight director (sides). All three were independent so any mode to be used with the autopilot (eg ALT HOLD or VOR/LOC) had to be selected three times. HDG SEL and VOR/LOC could be coupled to the autopilot but would only be driven by the heading bug set on the Captains compass and the course set on the Captains HSI. The SP-77 autopilot consisted of a Pitch Control Computer and a Roll Computer. For a dual-channel configuration, there were two Pitch Computers. Airplanes with this configuration had separate Flight Director controllers for the FD-108, FD-109, or FD-110 system, whichever was installed. The FD controllers were either built into the ADIs and HSIs, or were of various shapes and sizes with different combinations of switches and position nomenclatures. Modes available were GA, OFF, HDG, VOR LOC, AUTO APP & MAN GS, which was mainly used for capturing the glideslope from above!. There is also a PITCH CMD knob which has now become vertical speed. The centre panel is for autopilot selections and has two paddles to engage/disengage the ailerons and elevators "AIL" & "ELEV" for roll and pitch modes and could be engaged separately or together. The LH knob has the roll modes of HDG, VOR LOC, AUTO APP & MAN G/S and has a HDG OFF / HDG SEL switch to its right (see para 1). The RH knob has pitch modes of ALT HOLD or TURB. The TURB mode was controlled by the vertical gyro to allow smoother movements to regain altitude during turbulence. Some also had an ALT SEL mode. The small knob at the top, left of centre labelled "A", "B", "AB", is the hydraulic system selector source for the autopilot. Virtually none of the early 737-1/200's had ALT Select or Speed Select and were flown most of the time in CWS (Control Wheel Steering) - it was used like a sort of sophisticated  "wing leveller". The A/P was then "Flown" via the normal controls.

737-100/200 option

This asymmetric looking version of the MCP, was the first to have heading and course windows. Although everything looks biased to the LHS it is more First Officer friendly because he can set a heading (centre window) or course (the two outside windows) on this panel rather than having to rely on what the Captain sets on his compass or HSI. The usual F/D MODE SEL, ALT HOLD & PITCH CMD controls are all in this single panel and are repeated to both the Capt's and F/O's F/D's. The autopilot panel is displaced to the right.

737-200Adv

Toward the end of its production run, the Adv was fitted with an SP177 autopilot with integrated PDCS/FMC and automatics and in 1982 became Cat IIIa autoland capable. The Adv mode control panel has remained virtually unchanged through to the NG's. The differences between this -200Adv MCP and the -300+ MCP are: EPR button became N1 VNAV/PDC became VNAV No ALT or SPD INTV buttons fitted. Number tapes in windows instead of LCD's

737-300/400/500

The classics were fitted with Sperry SP-300 autopilot-flight director system (AFDS). This early -300 panel has paddles to engage & disengage autopilots and CWS. The two small grey panels either side of the MCP are to select the source of navigation information. The options are FMC (normal mode), ANS-L or ANS-R if the alternate navigation system (IRS based) is required.On pre-1991 MCP's, turning the altitude knob changed MCP altitude in 1000ft increments, when pressed in it changed to 100ft increments. Differences between various MCP's are: The A/P CMD/CWS/Disengage paddles changing to select buttons, or a mixture of both (see below). ALT & SPD INTV buttons for FMC hard speed and alt restraints, (covered by blanking plates with some operators).

This -500 has no ANS so those side panels are missing. They are replaced in this aircraft by stopwatch buttons, much more useful! The two blanking plates in the MCP are for the SPD INTV & ALT INTV options.

737-NG

The basic Honeywell (formerly Sperry) MCP is virtually unchanged from the 200ADVs but the EFIS control panels have been moved into the glareshield from the aft electronics panel in a similar arrangement to the 747-400. The latest Honeywell FCC software, P/N 2216-HNP-03B-10 OPS (known as “-710” software) - Aug 2007 Its features include: Added the capability to arm VNAV prior to selection of Takeoff when compatible CDS and FMC part numbers are also installed. When armed, pitch takeoff will transition to VNAV engage at 400 feet. Note, due to inconsistencies associated with the arming of VNAV prior to takeoff, Boeing released the reference a) ops manual bulletin instructing flight crews to not attempt arming VNAV on the ground prior to takeoff. Added the capability to arm LNAV prior to selection of Takeoff when compatible CDS and FMC part numbers are installed. When armed, the takeoff roll mode will transition to LNAV engage at 50 feet. Revised design of “flight director only” LNAV ARM to LNAV ENG in roll go around to allow auto engagement of LNAV from Track Hold down to 50 feet whether the flight director switches are on or off. Note: This function is available as an option. This option is activated by incorporation of a negotiated Boeing Service Bulletin that will specify the correct FCC software, FMC software, CDS OPS and OPC software. Added logic to reduce false altitude acquires due to erroneous but un-flagged altitude inputs.

From line number 1278 onwards (Feb 2003) the Rockwell Collins enhanced MCP was introduced. This was designed to operate with the new Collins enhanced digital flight control system with integrates the autothrottle computer and Flight Control Computer (FCC) to enable Cat IIIb autoland. Note the Cat IIIb EDFCS has a rudder servo and can perform an engine out autoland. Most of the knobs have been redesigned and the buttons have the caption printed on them instead of on the panel. Notice the different angle of bank selector. There are Boeings comments upon how the new MCP was designed: "Collins provided a preliminary MCP design to Boeing in 2000 for Boeing pilots and airline pilots to evaluate in the simulator and comment on. Based upon those comments, a revised MCP was installed on a test 737NG in November 2001. Boeing test pilots evaluated that design for approximately 4 months. Based upon that evaluation, changes were made in the tactile, lighting and thermal characteristics to increase the similarity of the Collins and Honeywell MCPs. The goal during this evaluation was to make the Collins MCP operationally transparent to the flight crew when compared with the Honeywell MCP. Recent certification and service-ready testing has indicated that the latest Collins MCP has obtained a high level of crew transparency."   Flight Control Computer (FCC) The FCC is the brains of the Digital Flight Control System (DFCS) and like any other computer, its software is being improved (and debugged !) all the time. There are two identical FCC's in each aircraft and although either one is capable of managing all of the DFCS functions, both are required for Cat III autoland and autopilot go-around operation. The latest Collins FCC software, P/N 2275-COL-AC1-06 (known as “-150” or “P5.0” software) - Jun 2007 Its features include: Added changes in the application program associated with selection of the 737-900ER model pin (including a variable flare height). Removed a “pitch bump” which can occur when glide slope is captured from above. Eliminated the cause of a disconnect which may occur when flying dual channel autopilot go-arounds on the Alpha submode. Changed the ratcheted Radar Altimeter rate limit (used for ILS gain programming) from 21 to 50 feet per second to allow faster updating of rapid rises in approach terrain. Insured that an invalid minimum speed input disengages the VNAV mode or prevents entry into the VNAV mode.