Date: 201809
Local time of day: 1201-1800
Location: TTN.Airport, NJ
Flight conditions: Marginal
Weather elements / visibility: 4
Aircraft: Helicopter
Operator: Fractional
Operating under: Part 91
Flight plan: None
Mission: Ferry / Re-Positioning
Flight phase: Cruise
Airspace: Class E PHL
ATC / advisory: TRACON PHL
Reporter organization: Fractional
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Distraction; Troubleshooting; Workload
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter VFR In IMC
Detector: Person Flight Crew
When detected: In-flight
Contributing factors: Procedure; Weather; Human Factors
Primary problem: Weather

Narrative: An IFR flight plan had been filed for the portion of the planned flight to TTN. However the PIC decided to proceed VFR on the flight because the destination was reporting 2100 broken with 4 miles visibility and other airports along the route were reporting similar weather. The aircraft was a helicopter.The flight left at approximately XX:35 and proceeded southwest bound at 1500 feet; well below cloud cover and with good visibility. At approximately 10 miles northeast of TTN the ceiling began to lower. The aircraft started a descent to 1200 feet and turned toward the northwest to maintain VFR. The aircraft continued to the northwest until it was approximately 10 miles due north of TTN; and had descended to 1000 to maintain VFR.The aircraft then turned south and called TTN tower for clearance in to the Class D. TTN tower radar identified the aircraft; and gave clearance into the Class D. As the aircraft proceeded southbound the ceiling continued to lower. The PIC was expecting improvement in ceiling as they continued to the airport because the METAR at XX:00 was reporting 2100 feet broken. (Though the METAR was changing at XY:00; that report was still 1600 feet broken)When the aircraft was at approximately 7-8 miles north of TTN; and now at 700 ft as the ceiling continued to lower; the PIC instructed the SIC to tell TTN tower that the aircraft was contacting PHL approach control to pick up the IFR clearance in order to continue IFR into TTN. The SIC complied; and then contacted PHL approach control for clearance. The PIC started a right turn back to the north to avoid the TTN Class D airspace; and began a climb. As the SIC was receiving a transponder code and clearance from PHL; the aircraft encountered inadvertent IMC.After being radar identified; the aircraft was given a radar vector to the west for the ILS to runway 6; and a climb to 3000 for the approach. The aircraft proceeded on the ILS without incident; however; the aircraft did not break out on the ILS until approximately 800 feet.I am not certain why it is that some airports do not seem to update their METARS in a more timely fashion. I also am not completely certain how an airport can report a 2100 foot ceiling and have it be so much lower in reality.Weather reports are more or less factual; and are depended on to a great extent to plan flights and options to flights. If reporters are not diligent in keeping up with changes in conditions and reporting them. Pilots cannot effectively; or safely; plan and execute their missions.This is not the first time I have encountered conditions at an airport in the northeast area that were very different from what was being reported.




Synopsis: Helicopter pilot reported an inaccurate METAR prevented continuing to the airport VFR when the weather was IFR and getting worse.