Aviation Investigation Report A98H0003

1.6.7  Warnings and Alerts

The MD-11 alerting system incorporates master warning and master caution lights on the glareshield. Alerts are displayed in the cockpit on the EAD, the SD, or both. Alerts are categorized into four levels (3, 2, 1, and 0) and are presented in three columns in the lower third of the EAD.

Level 3 (red) alerts indicate emergency operational conditions that require immediate flight crew awareness and immediate corrective or compensatory action by the pilots. All Level 3 alerts have an aural warning. Level 2 (amber) alerts indicate abnormal operational system conditions that require immediate flight crew awareness and subsequent corrective or compensatory action by the pilots. Level 1 (amber) alerts may require a maintenance action prior to take-off, a logbook entry, or confirmation of desired system configuration. A Level 1 (amber) alert in flight may require flight crew action as prompted, and requires an aircraft logbook entry. Level 0 (cyan) alerts usually indicate operational or aircraft systems status information.

If a system generates an alert or warning, the applicable cue switch on the system display control panel (SDCP) illuminates, enabling the pilots to identify the system. Activating the illuminated system cue switch on the SDCP produces the associated system synoptic page on the SD, and extinguishes the cue light, master warning, and caution lights, if they are on. Table 6 shows available cue switches and their associated systems synoptic page.

Table 6: Cue Switches and Associated Systems Synoptic Pages

Cue Switch Associated Systems Synoptic Page
ENG engine
HYD hydraulic system
ELEC electrical system
AIR air system
FUEL fuel system
CONFIG flight controls and landing gear
MISC alerts and consequences for various miscellaneous systems

The FDR revealed that the air system synoptic page (Air Page) was selected by the pilots sometime between 0111:49 and 0112:52, shortly after the unusual odour was first detected in the cockpit. This page displays environmental system operation of the manifolds, duct temperatures, zone temperatures, smoke and heat detectors in the cargo compartments, pressurization readouts, bleed-air readout, and air conditioning pack readouts. Aside from the flight crew selection of the Air Page, the FDR records only the following potentially related data: air packs 1, 2, and 3 OFF; aft and forward cargo heat; bleed-airs 1, 2, and 3 OFF; cabin pressure warning; and cabin altitude warning. The FDR does not record individual duct or zone temperatures, cabin smoke, lavatory smoke, or any system cues displayed on the SDCP.

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