Dash 8 captain reported deviating from assigned altitude to follow TCAS RA commands.

Attributes
ACN	1383428
Time
Date	201608
Local Time Of Day	1201-1800
Place
Locale Reference	ABE.Airport
State Reference	PA
Environment
Light	Daylight
Aircraft 1
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 245 Flight Crew Total 2780 Flight Crew Type 1280
Events
Anomaly	Conflict NMAC Deviation - Altitude Excursion From Assigned Altitude
Miss Distance	Horizontal 200 Vertical 300

Narrative:

While enroute and 22 miles south [of] allentown airport; our TCAS issued an RA to descend 2000 feet per minute; which deviated us from our assigned altitude (4;000 ft) 500 ft below. After the TCAS was off we went back to our assigned altitude and advised ATC.[suggest] better altitude flight planning for that specific route will help such as higher altitude.

Original NASA ASRS Text

Title: Dash 8 Captain reported deviating from assigned altitude to follow TCAS RA commands.

Narrative: While enroute and 22 miles south [of] Allentown airport; our TCAS issued an RA to descend 2000 feet per minute; which deviated us from our assigned altitude (4;000 ft) 500 ft below. After the TCAS was off we went back to our assigned altitude and advised ATC.[Suggest] better altitude flight planning for that specific route will help such as higher altitude.

Data retrieved from NASA's ASRS site 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.