SAIB 2026-17

FAA Aviation Safety

SPECIAL AIRWORTHINESS

INFORMATION BULLETIN SUBJ: VNAV Approach Disconnect Following Missed Approach, Anomaly on Airplanes with FMC U14.0/14.1 SAIB: 2026-17 Date: October 3, 2026 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin advises owners and operators of The Boeing Company Model 737-600/-700/-800/-900/-900ER/-7/-8/-9/-8200 airplanes of the possibility of vertical navigation (VNAV) mode disconnecting during the subsequent approach after a missed approach with Flight Management Computer (FMC) software version U14.0 or U14.1 installed.

At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.

Background

Boeing was notified of an error in the flight management software that affects the airplane’s VNAV system with FMC software versions U14 or U14.1 installed on the aircraft identified above. This anomaly occurs with the following conditions:

• After a missed approach.

• When the flight crew navigates direct to a waypoint that is not part of any approach or approach transition associated with that airport.

This anomaly results in the transition from a vertical navigation mode to a simpler level of automation for pitch control during the subsequent approach. When this occurs, the pilots would need to perform additional procedural steps if they intend to use vertical navigation on subsequent approaches. Boeing took this issue to their safety review board and made the determination that this event should not be considered to pose an unsafe condition. Independently, the FAA took this issue to our corrective action review board and made the determination that this event does not represent an unsafe condition. This issue will not require mandated actions at this time.

Recommendations

Boeing developed the referenced guidance for addressing this scenario.

• Boeing Fleet Team Digest: 737MAX-FTD-34-25003, “VNAV Disconnect Upon Raising the MCP Altitude For a Missed Approach when a Go-Around has been Performed”, revision dated October 2, 2026

• Boeing Fleet Team Digest: 737NG-FTD-34-26002, “VNAV Disconnect Upon Raising the MCP Altitude For a Missed Approach when a Go-Around has been Performed”, dated October 2, 2026

• Boeing Flight Crew Operations Manual Bulletin, OMB Number: PCR-3808, “VNAV Approach Disconnect Following Missed Approach, Anomaly on Airplanes with FMC U14.0/14.1”, dated October 2, 2026

The FAA recommends that all owners and operators of affected airplanes follow the published guidance that was developed for addressing this scenario.

For Further Information Contact

Nathan Weigand, Acting Manager, AIR-520 Continued Operational Safety Branch, phone: 817-222- 5390; e-mail: operationalsafety@faa.gov.