A single engine aircraft pilot on the PYE1 arrival encountered turbulence at 5;000 ft resulting in a...

Narrative:

I was flying in light to moderate turbulence (for a cherokee) hearing PIREPS from large and even heavy aircraft to ATC that they were experiencing moderate turbulence (for a large aircraft) below 4;500 MSL over the mountains. I was 5;000 MSL over water on the arrival having requested a visual approach in cavu conditions; when I first had held altitude in an updraft that necessitated cutting power to idle and nose down at vno; when the aircraft entered a very strong downdraft that caused me to lose 400 ft before I could arrest the descent at vy with full power. ATC frequency was busy; but I managed to get in about one minute later; 'nxxx is having trouble holding altitude.' ATC then told me that they didn't have a mode C report; and asked for my present altitude. I replied honestly that I was now at 4;700 climbing very slowly; but that I had been at 4;600. ATC then offered a higher altitude; but as I expected to be descending soon (and was soon there after) with vectors to my destination; I declined. ATC then told me that they would keep other aircraft away from me. They kindly kept me at 5;000 as late as possible so that I could descend through the turbulence as quickly as possible. I'm pretty sure that ATC did not get miffed at my altitude bust; though it concerned me (I like flying... And try hard to be safety conscious.) I had done my preflight weather briefing through aviation weather.gov; followed by another flight planner when I filed. I don't recall seeing any sigmets or airmets that would have caused me alarm. Light to moderate turbulence is a fact of life for small aircraft. But; I am concerned that my mode C was not seen... I've checked it several times since I've owned the aircraft. It's working. It has been inspected regularly. Yet; when I'm in class B during certain times; the response light is on more than off! I am concerned that with growing popularity of TCAS; that the once every 12 second sweep of the radar misses my transponder because it is already busy responding to another aircraft's TCAS? This could be a safety issue. Will ads-B fix this?

Original NASA ASRS Text

Title: A single engine aircraft pilot on the PYE1 arrival encountered turbulence at 5;000 FT resulting in a 400 FT altitude loss but ATC was very understanding and replied the aircraft's transponder was not received.

Narrative: I was flying in light to moderate turbulence (for a Cherokee) hearing PIREPS from large and even heavy aircraft to ATC that they were experiencing moderate turbulence (for a large aircraft) below 4;500 MSL over the mountains. I was 5;000 MSL over water on the arrival having requested a visual approach in CAVU conditions; when I first had held altitude in an updraft that necessitated cutting power to idle and nose down at Vno; when the aircraft entered a very strong downdraft that caused me to lose 400 FT before I could arrest the descent at Vy with full power. ATC frequency was busy; but I managed to get in about one minute later; 'NXXX is having trouble holding altitude.' ATC then told me that they didn't have a Mode C report; and asked for my present altitude. I replied honestly that I was now at 4;700 climbing very slowly; but that I had been at 4;600. ATC then offered a higher altitude; but as I expected to be descending soon (and was soon there after) with vectors to my destination; I declined. ATC then told me that they would keep other aircraft away from me. They kindly kept me at 5;000 as late as possible so that I could descend through the turbulence as quickly as possible. I'm pretty sure that ATC did not get miffed at my altitude bust; though it concerned me (I like flying... and try hard to be safety conscious.) I had done my preflight weather briefing through aviation weather.gov; followed by another flight planner when I filed. I don't recall seeing any SIGMETS or AIRMETS that would have caused me alarm. Light to Moderate Turbulence is a fact of life for small aircraft. But; I am concerned that my Mode C was not seen... I've checked it several times since I've owned the aircraft. It's working. It has been inspected regularly. Yet; when I'm in Class B during certain times; the response light is on more than off! I am concerned that with growing popularity of TCAS; that the once every 12 second sweep of the radar misses my transponder because it is already busy responding to another aircraft's TCAS? This could be a safety issue. Will ADS-B fix this?

Data retrieved from NASA's ASRS site as of April 2012 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	982902
Time
Date	201112
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft Low Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Transponder
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Commercial Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 860 Flight Crew Type 680
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence

A single engine aircraft pilot on the PYE1 arrival encountered turbulence at 5;000 ft resulting in a 400 ft altitude loss but ATC was very understanding and replied the aircraft's transponder was not received.