Narrative:

We were doing a part 91 repositioning flight from ZZZ to hpn. I was the pm sitting in the left seat. After receiving multiple vectors and a speed reduction; we were cleared for the RNAV (GPS). We had previously loaded and briefed that approach. Prior to reaching bodre; the PF asked for gear down; before landing checklist. I complied while thinking to myself it was a little early for that action. The approach controller instructed us to contact tower. As I reached up to change frequencys; the GPWS sounded a terrain warning and a pull up command. It took a few seconds for me to realize the PF was starting his descent to MDA prior to the FAF (CZ1MR). The hpn tower advised us of a low altitude alert and to check our altitude. The PF climbed back to the correct altitude and we continued the approach and landed. The PF stated he thought we were approaching the FAF when he called for gear down. This was our first flight together. I should have verbalized my thoughts to the PF about putting the gear down so early. Although; the ATIS; which was an hour old; indicated an overcast condition; the sky was actually broken during our descent; vectors; and all during the approach.

Related reports:

Google
 

Original NASA ASRS Text

Title: A CE560 CAPT AS PM ALLOWED THE FP FO TO DESCEND PRIOR TO THE FAF. A GPWS TERRAIN WARNING AS WELL AS ATC LOW ALT ALERT WERE GIVEN.

Narrative: WE WERE DOING A PART 91 REPOSITIONING FLT FROM ZZZ TO HPN. I WAS THE PM SITTING IN THE L SEAT. AFTER RECEIVING MULTIPLE VECTORS AND A SPD REDUCTION; WE WERE CLRED FOR THE RNAV (GPS). WE HAD PREVIOUSLY LOADED AND BRIEFED THAT APCH. PRIOR TO REACHING BODRE; THE PF ASKED FOR GEAR DOWN; BEFORE LNDG CHKLIST. I COMPLIED WHILE THINKING TO MYSELF IT WAS A LITTLE EARLY FOR THAT ACTION. THE APCH CTLR INSTRUCTED US TO CONTACT TWR. AS I REACHED UP TO CHANGE FREQS; THE GPWS SOUNDED A TERRAIN WARNING AND A PULL UP COMMAND. IT TOOK A FEW SECONDS FOR ME TO REALIZE THE PF WAS STARTING HIS DSCNT TO MDA PRIOR TO THE FAF (CZ1MR). THE HPN TWR ADVISED US OF A LOW ALT ALERT AND TO CHK OUR ALT. THE PF CLBED BACK TO THE CORRECT ALT AND WE CONTINUED THE APCH AND LANDED. THE PF STATED HE THOUGHT WE WERE APCHING THE FAF WHEN HE CALLED FOR GEAR DOWN. THIS WAS OUR FIRST FLT TOGETHER. I SHOULD HAVE VERBALIZED MY THOUGHTS TO THE PF ABOUT PUTTING THE GEAR DOWN SO EARLY. ALTHOUGH; THE ATIS; WHICH WAS AN HR OLD; INDICATED AN OVCST CONDITION; THE SKY WAS ACTUALLY BROKEN DURING OUR DSCNT; VECTORS; AND ALL DURING THE APCH.

Data retrieved from NASA's ASRS site as of January 2009 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.