> ## Documentation Index
> Fetch the complete documentation index at: https://www.narev.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Before taxi — part 1

> Before taxi — part 1: conditions, actions and checks for the Boeing 737-800.

Use this procedure when its prerequisites apply. Confirm each required aircraft state before acknowledging the corresponding checklist item.

## General

Enter this procedure after completion of the engine-start sequence and verification of the applicable engine-running condition. The start-lever IDLE check confirms the completed configuration; it does not replace the N2-gated fuel-admission steps in [Engine Start](https://www.narev.ai/docs/irl-gym/aircraft/procedures/engine-start-1.md).

Complete generator, heat, air-system and start-switch selections. Verify ground equipment clear, the assigned takeoff flap configuration and the required flight-control check before taxi movement. Use the assigned taxi route and steering/braking procedure.

### 1. Generators 1 and 2 — **On**

After completion of the engine-start procedure, select generators 1 and 2 ON. Verify the required generator and bus indications.

> **Checks and evidence**
>
> **Expected response:** ON
>
> **Verification:** Verify both generator switch/source outcomes and actual bus supply.

### 2. Probe heat — **On**

Apply the checklist’s literal OFF or ON requirement to all applicable probe heat systems for the configured aircraft.

> **Checks and evidence**
>
> **Expected response:** ON
>
> **Verification:** Confirm the relevant switch states and both probe-system outcomes.

### 3. Wing anti-ice — **As needed**

For an explicit OFF, establish OFF. For As needed, first resolve the mission’s icing decision using an approved policy; do not infer it from temperature alone.

> **Checks and evidence**
>
> **Expected response:** As needed
>
> **Verification:** Verify the selected switch state and the relevant valve/annunciator outcome under a the applicable decoder.

### 4. Engine anti-ice — **As needed**

Apply the required anti-ice state to the applicable engines; resolve As needed before issuing a command.

> **Checks and evidence**
>
> **Expected response:** As needed
>
> **Verification:** Require switch-state and corresponding system/annunciator evidence.

### 5. Pack switches — **Auto**

Set both pack switches AUTO. Verify both selector positions using the applicable detent decoding.

> **Checks and evidence**
>
> **Expected response:** AUTO
>
> **Verification:** Read both selector states and confirm the requested detent.

### 6. Isolation valve — **Auto**

Select the isolation-valve selector AUTO. Verify the selector position; verify actual valve state separately when required.

> **Checks and evidence**
>
> **Expected response:** AUTO
>
> **Verification:** Decode and compare the selector position; verify physical valve state separately where required.

### 7. APU bleed — **Off**

Select APU bleed OFF in accordance with the applicable air-supply configuration. Verify the required switch and valve indications.

> **Checks and evidence**
>
> **Expected response:** OFF
>
> **Verification:** Require APU bleed-switch/valve state and relevant source evidence.

### 8. APU switch — **As needed**

Resolve the required APU state for this phase from the mission’s electrical/air plan, then use a validated APU switch procedure.

> **Checks and evidence**
>
> **Expected response:** As needed
>
> **Verification:** Verify selector and APU availability/outcome, not just EGT.

### 9. Engine start switches — **Cont**

Select both engine start switches CONT. Verify both rotary-switch positions. These switches are separate from the fuel/start levers.

> **Checks and evidence**
>
> **Expected response:** CONT
>
> **Verification:** Require both applicable rotary-switch states.

## Continue after this procedure

Continue to [Before taxi — part 2](https://www.narev.ai/docs/irl-gym/aircraft/procedures/before-taxi-2.md). The checklist adds no condition between these parts; the next part’s individual step conditions still apply.


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