The U.S. aircraft register, updated daily
Approved modifications · supplemental type certificate · current · issued

ST00927CH

Installation of a Honeywell electronic flight instrument system, digital flight guidance computer, and central aural warning system. Held by Midwest Express Airlines, which holds 6 approved modifications in all. Last revised September 4, 1998. System: instruments and avionics.

What it applies to

Kind of product
Aircraft
Design holder
McDonnell Douglas Corporation; McDonnell Douglas Corporation
Models
DC-9-82 (MD-82), DC-9-81 (MD-81)
Type certificates
A6WE, A6WE
On this site
Mcdonnell Douglas DC-9 93 registered
The FAA's record
On the FAA's site

What an approved modification is

A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.

Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 20, 2026.