B737-900 flight crew reports missing a crossing restriction during arrival due to the aircrafts tend...

Narrative:

Strong tailwinds in descent; turbulence; and then entered an area of scattered rain showers. As the non flying pilot; I monitored first officer during descent. Flying new 737-900 that has a tendency to revert from VNAV path to VNAV speed with the slightest airspeed deviation. Caught aircraft at least twice leaving VNAV path and reverting to VNAV speed. First officer was planning on making landing to runway 22L. Winds were reported 5 KTS down the runway. Just prior to 10;000 ft; switched to approach control; heard ATC telling aircraft ahead of us now switching to runway 4 right for landing. Wind now 330 degrees at 24 KTS. I immediately announced I will reprogram the box (FMC) for 4R and sent for a new ATIS; first officer began to retune own radio for 4R. I then asked first officer if new wind was greater than allowed since first officer was new and high minimums. First officer stated 'you have the aircraft and I will look (or something to that extent).' I announced I had control of the aircraft and first officer fairly quickly produced high mins restriction sheet and we both realized first officer was prohibited from making the landing. At this point; I reached up and selected autopilot a and looked down to verify ap switched properly via the FMA. At this point I realized the aircraft had yet again tripped from VNAV path to VNAV speed and we were just below 10;000 ft approaching waypoint dylin which we were supposed to cross at 8;000 ft.

Original NASA ASRS Text

Title: B737-900 flight crew reports missing a crossing restriction during arrival due to the aircrafts tendency to come out of VNAV path into VNAV speed with the slightest provocation. The descent is unmonitored for a few moments while the FP/NFP switch roles and a new runway is entered in the FMC.

Narrative: Strong tailwinds in descent; turbulence; and then entered an area of scattered rain showers. As the Non Flying Pilot; I monitored First Officer during descent. Flying new 737-900 that has a tendency to revert from VNAV Path to VNAV Speed with the slightest airspeed deviation. Caught aircraft at least twice leaving VNAV path and reverting to VNAV speed. First Officer was planning on making landing to Runway 22L. Winds were reported 5 KTS down the runway. Just prior to 10;000 FT; switched to approach control; heard ATC telling aircraft ahead of us now switching to Runway 4 Right for landing. Wind now 330 degrees at 24 KTS. I immediately announced I will reprogram the box (FMC) for 4R and sent for a new ATIS; First Officer began to retune own radio for 4R. I then asked First Officer if new wind was greater than allowed since First Officer was new and High Minimums. First Officer stated 'You have the aircraft and I will look (or something to that extent).' I announced I had control of the aircraft and First Officer fairly quickly produced high mins restriction sheet and we both realized First Officer was prohibited from making the landing. At this point; I reached up and selected autopilot A and looked down to verify AP switched properly via the FMA. At this point I realized the aircraft had yet again tripped from VNAV Path to VNAV Speed and we were just below 10;000 FT approaching waypoint DYLIN which we were supposed to cross at 8;000 FT.

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.

Attributes
ACN	1156785
Time
Date	201403
Local Time Of Day	0001-0600
Place
Locale Reference	N90.TRACON
State Reference	NY
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Descent
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 200 Flight Crew Total 14000 Flight Crew Type 10000
Person 2
Function	First Officer Pilot Flying
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Inflight Event / Encounter Weather / Turbulence

B737-900 flight crew reports missing a crossing restriction during arrival due to the aircrafts tendency to come out of VNAV path into VNAV speed with the slightest provocation. The descent is unmonitored for a few moments while the fp/nfp switch roles and a new runway is entered in the FMC.