Assisted by approach control; a saab 340 experiencing hydraulic system problems conducted a flawed m...

Narrative:

I was working sectors X/Y/xx at the time. The saab was cleared for a VOR runway approach to ZZZ. Soon ZZZ FSS called and said that the flight was on the missed approach and was coming back to my frequency. On contact I stated to the pilot to execute the published missed approach and when able say intentions. Soon after he stated that they wished to climb to 070 and divert direct to ZZZ1. I told the pilot to climb and maintain 040 in the hold; reaching 040 cleared direct ZZZ1 then climb and maintain 070. Pilot stated that he wanted direct at 070 again. I noticed that the pilot was not flying the published missed approach and headed towards higher terrain. I issued a low altitude alert and received no response from the aircraft. He soon turned towards ZZZ1 and planned the visual approach. About half way from ZZZ to ZZZ1 I asked the pilot if he would need any further assistance with me or ZZZ1 tower. At that time he declared an emergency; stating low hydraulic pressure and was unsure if their braking was going to be able to work. Gear was locked [down with] three in the green. I did manual coordination with ZZZ1 tower on all emergency information and intentions. Later they landed safely but were unable to taxi off the runway. If the pilot is unable to execute the published missed; they should tell the controller immediately. Then different instructions can be given to the pilot based on aircraft performance; emergency situation.

Original NASA ASRS Text

Title: Assisted by approach control; a SAAB 340 experiencing hydraulic system problems conducted a flawed missed approach procedure at ZZZ and diverted to ZZZ1 where they landed safely but were unable to taxi off the runway.

Narrative: I was working sectors X/Y/XX at the time. The Saab was cleared for a VOR RWY approach to ZZZ. Soon ZZZ FSS called and said that the flight was on the missed approach and was coming back to my frequency. On contact I stated to the pilot to execute the published missed approach and when able say intentions. Soon after he stated that they wished to climb to 070 and divert direct to ZZZ1. I told the pilot to climb and maintain 040 in the hold; reaching 040 cleared direct ZZZ1 then climb and maintain 070. Pilot stated that he wanted direct at 070 again. I noticed that the pilot was not flying the published missed approach and headed towards higher terrain. I issued a low altitude alert and received no response from the aircraft. He soon turned towards ZZZ1 and planned the visual approach. About half way from ZZZ to ZZZ1 I asked the pilot if he would need any further assistance with me or ZZZ1 Tower. At that time he declared an emergency; stating low hydraulic pressure and was unsure if their braking was going to be able to work. Gear was locked [down with] three in the green. I did manual coordination with ZZZ1 Tower on all emergency information and intentions. Later they landed safely but were unable to taxi off the runway. If the pilot is unable to execute the published missed; they should tell the controller immediately. Then different instructions can be given to the pilot based on aircraft performance; emergency situation.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1126255
Time
Date	201311
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Aircraft 1
Make Model Name	Saab 340 Undifferentiated
Operating Under FAR Part	Part 121
Route In Use	Other Instrument Approach
Flight Plan	IFR
Component
Aircraft Component	Hydraulic System
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Critical Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Assisted by approach control; a saab 340 experiencing hydraulic system problems conducted a flawed missed approach procedure at ZZZ and diverted to ZZZ1 where they landed safely but were unable to taxi off the runway.