CAS Philosophy

James Albright

Updated: 2019-07-05

Yes, Gulfstream has reinvented the way we look at the CAS. And they've done a pretty good job of it too. If you understand how CAS messages are displayed and filtered, you will have a much easier time making V1 and troubleshooting decisions.

 A New CAS Message Philosophy

CAS Messages are no longer strictly grouped in Red, Amber, Cyan, White order and then, within a color grouping grouped with the most recent on top. Now when a particular CAS message can be said to have caused other CAS messages, that CAS message is called an Umbrella CAS and will have a "(U)" placed at its end. The messages that were caused as a result are called "Consequential Alert" messages and are preceded by a ">" symbol. And there are more changes. But the bottom line is that you will be able to more quickly discern the important messages from those that are just results.

[AFM, §00-20-70]

CAS Message Definition

1. Warning Messages: Time critical warning alert. A condition that requires immediate flight crew awareness and immediate flight crew response.

2. Caution Messages: Time critical caution alert. A condition that requires immediate flight crew awareness and subsequent flight crew response.

3. Advisory Messages: Non-time critical alert. A condition that requires flight crew awareness and may require subsequent flight crew response.

4. Status Messages: System status/selection based on system feedback or switch selection that do not require an alert and do not require pilot action.

Single System CAS Messages

1. Single system CAS messages only impact a single aircraft system or subsystem and normally do not cause other system failures. Example: Speed Brakes Extended (caution)

Umbrella System CAS Messages

1. An umbrella CAS message is presented in lieu of two or more CAS messages that share a common cause. An umbrella CAS is identified with “(U)” following the message. Example: BFCU Active (U) (caution)

2. Umbrella CAS messages always have at least one Consequential Alert (CA) CAS Message associated with the primary message. The CA message shares a common cause with the umbrella message and can be either displayed or non-displayed. A displayed CA message is identified on the CAS window with a “>” in front of the message and is always listed directly below the associated umbrella CAS message. Example:
   APU Door (U) (caution)
   >APU Fail (caution)
   Certain warning CAS messages use the displayed consequential alert to notify aircrew of an action that should be accomplished without delay. For example, the Engine Fire warnings are presented below with a time critical displayed consequential alert.
   L Engine Fire (U) (warning)
   >Reduce L Throttle To Idle (warning)

3. All Displayed CA messages meet one of the following:

   • A directive statement associated with warning CAS messages

   • Reduction in the aircraft flight envelope

   • Degraded flight or ground controls

   • Degraded ECS or CPCS

   • Loss of further annunciations or alerts

   • Consideration for AOG status

4. Non-displayed CA messages also share a common cause with the umbrella message but do not meet any of the displayed CA criteria. The corrective actions contained within AFM procedures for umbrella CAS messages include all steps for both displayed and non-displayed CA messages. Occasionally, when an umbrella CAS message displays, additional CAS messages that are not consequential alerts may display. In these cases, the AFM corrective actions for these additional messages must also be accomplished.

5. There are some exceptions for umbrella CAS messages. Modular Power Tile (MPT) failures are an example. The systems powered by an MPT may have alternate power paths or system state communication failures which prohibit the absolute certainty of system status required for an umbrella CAS message. In these cases, additional single system CAS message may actually be the common cause of other CAS messages presented to the crew. Example: DC MPT 1 Fail (caution) CAS message

6. In these cases, all the CAS messages associated with the single underlying failure will appear in the CAS window at approximately the same time. Usually, the underlying failure will be the first message to appear, placing it at the bottom of the CAS stack, for its assigned alert level. In these cases where multiple CAS messages appear nearly simultaneously without an umbrella CAS message, the crew should first address the bottom message of the highest alert level of the new CAS messages. The crew is required to review the AFM procedures for each display CAS message.

Collector CAS Messages

1. A Collector CAS message is a single alert message that has multiple possible causes. The procedure includes information on the possible causes of the message. Example: Service Door (advisory) CAS message. In this example, one or more exterior service door(s) are not closed and latched. The pilot actions would include a determination of which service door(s) are not closed and latched. In most cases, open service doors may be identified on the Doors synoptic page.

  CAS Filtering

[AOM, §2B-07-30]

• Global inhibits are designed for CAS messages so that the displaying or clearing of non-critical CAS messages does not distract the crew during the takeoff or landing phases of flight. CAS messages on which global inhibits are applied are held at the same status during the inhibit phase. Two examples of this is as follows:

  • If the message is not displayed before the inhibit segment, and while in the inhibit segment the message logic is activated, the message is not displayed on the CAS window until the inhibit segment is complete.

  • If the message is displayed before the inhibit segment, and while in the inhibit segment the message logic is deactivated, then the message is not removed from the CAS window until the inhibit segment is complete.

  NOTE: Critical CAS messages are always displayed during the takeoff and/or landing phases of flight.

1. Low Speed Takeoff Filtering

   Some messages are not displayed during both the low speed and high speed segments of takeoff until safely airborne. Some examples of these messages include, but are not limited to: DU 3 Overheat, Cabin Phone Call, and Strobe Lights Off.

   An example of how low speed filtering works is as follows:

   • L Thrust Rev Fail is not displayed during the low speed segment of the takeoff

   • If L Thrust Rev Fail occurs below 60 KCAS, it is displayed

   • If L Thrust Rev Fail occurs above 60 KCAS, it is not displayed until the airborne conditions are met, as shown in Figure 6.

2. High Speed Takeoff Filtering

   Some messages are not displayed during the high speed segment of takeoff until safely airborne. Some examples of these messages include, but are not limited to: L Oil Temperature Low, BFCU Active (U), and L OUTBD BRK Degrade.

   An example of how high speed filtering works is as follows:

   • BFCU Active (U) is not displayed during the high speed segment of the takeoff

   • If BFCU Active (U) occurs below V1-5 KCAS, it is displayed

   • If BFCU Active (U) occurs above V1-5 KCAS, it is not displayed until the airborne conditions are met, as shown in Figure 6.

   NOTE: If the V1 speed is not available or not calculated by the flight management system (FMS), the high speed takeoff inhibit remains inactive.

3. Landing Filtering

   Some messages are not displayed during the landing phase of flight. Some examples of these messages include, but are not limited to: Bleed Configuration, TSC 2 Fail, and NAV Lights Off.

   An example of how landing filtering works is as follows:

   • Bleed Configuration is not displayed during the landing segment

   • If Bleed Configuration occurs during the landing segment as defined in Figure 7, it is not displayed

   • 30 seconds after landing, Bleed Configuration is displayed.