Narrative:

This situation has continued for the past 2 yrs since I arrived here. The islands of stt and stx lie on a n-s course approximately 40 NM apart. My airline operates around 40 flts per day between the 2 islands, and there are numerous other companies flying passenger or cargo back and forth all day, and most of the early evening. As the WX is almost always VFR, most aircraft save time by going VFR. Even though VFR advisories are available from sju cerap on 127.4, most of the local pilots don't bother. Although the WX is mostly VFR, it is usually in the form of a scattered to broken layer of cumulus clouds between 1500 and 4000' MSL. If the layer is broken or overcast, nearly all aircraft opt for VFR, either under or over the clouds. Most will take the lower altitudes below 300' to avoid a VFR altitude of 3500' or 4500'. If the layer is scattered, aircraft will often fly through it, dodging clouds to remain VFR. Most of the aircraft fly at 1500, 2000 or 2500'. The hazard, I believe, is in the fact that there are dozens of aircraft who fly this narrow beeline corridor from stt or stx. Nearly all are below 300' on VFR flight plans and are receiving no advisory information. Many of the crews on these flts fly back and forth several times a day. I can tell you it's extremely boring. The possibility for a collision is very high under these conditions, especially when 2 opp direction aircraft are both navigating through the same cloud layer (VFR) at the same altitude. I have been surprised many times to see an oncoming aircraft pass within 1/4 mi of ours, yet no one spotted him until he was already passing our 2-3 O'clock position. The combination of extremely bright sunlight, the ocean below and the scattered clouds make it difficult to spot oncoming traffic from a safe distance, especially if you don't know it's there! The only effective solution I can see is for the local FAA office in sju to mandate certain altitudes for aircraft below 3000' on the stt/stx corridor. Specifically, 1000 or 2000' for nbnds to stt, and 1500 or 2500' for sbnds to stx. 3000' cannot be used for nbnds since this is an IFR altitude often assigned by ATC. All aircraft could be required to squawk mode C at one of these altitudes, or climb to a higher VFR altitude above 3000' (3500, 4500, etc). I hope that the FAA can see the logic in this before there is an accident. This simple procedure will merely organize the aircraft that already use these altitudes, instead of each air crew trusting to luck. It would be easy to implement and enforce, since I know many of our own pilots are concerned about it.

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Original NASA ASRS Text

Title: COMMUTER REPORTER IS CRITICAL OF THE # OF ACFT OPERATING AT LOW ALT BETWEEN STT AND STX WITHOUT ATC SERVICE.

Narrative: THIS SITUATION HAS CONTINUED FOR THE PAST 2 YRS SINCE I ARRIVED HERE. THE ISLANDS OF STT AND STX LIE ON A N-S COURSE APPROX 40 NM APART. MY AIRLINE OPERATES AROUND 40 FLTS PER DAY BTWN THE 2 ISLANDS, AND THERE ARE NUMEROUS OTHER COMPANIES FLYING PAX OR CARGO BACK AND FORTH ALL DAY, AND MOST OF THE EARLY EVENING. AS THE WX IS ALMOST ALWAYS VFR, MOST ACFT SAVE TIME BY GOING VFR. EVEN THOUGH VFR ADVISORIES ARE AVAILABLE FROM SJU CERAP ON 127.4, MOST OF THE LCL PLTS DON'T BOTHER. ALTHOUGH THE WX IS MOSTLY VFR, IT IS USUALLY IN THE FORM OF A SCATTERED TO BROKEN LAYER OF CUMULUS CLOUDS BTWN 1500 AND 4000' MSL. IF THE LAYER IS BROKEN OR OVCST, NEARLY ALL ACFT OPT FOR VFR, EITHER UNDER OR OVER THE CLOUDS. MOST WILL TAKE THE LOWER ALTS BELOW 300' TO AVOID A VFR ALT OF 3500' OR 4500'. IF THE LAYER IS SCATTERED, ACFT WILL OFTEN FLY THROUGH IT, DODGING CLOUDS TO REMAIN VFR. MOST OF THE ACFT FLY AT 1500, 2000 OR 2500'. THE HAZARD, I BELIEVE, IS IN THE FACT THAT THERE ARE DOZENS OF ACFT WHO FLY THIS NARROW BEELINE CORRIDOR FROM STT OR STX. NEARLY ALL ARE BELOW 300' ON VFR FLT PLANS AND ARE RECEIVING NO ADVISORY INFO. MANY OF THE CREWS ON THESE FLTS FLY BACK AND FORTH SEVERAL TIMES A DAY. I CAN TELL YOU IT'S EXTREMELY BORING. THE POSSIBILITY FOR A COLLISION IS VERY HIGH UNDER THESE CONDITIONS, ESPECIALLY WHEN 2 OPP DIRECTION ACFT ARE BOTH NAVIGATING THROUGH THE SAME CLOUD LAYER (VFR) AT THE SAME ALT. I HAVE BEEN SURPRISED MANY TIMES TO SEE AN ONCOMING ACFT PASS WITHIN 1/4 MI OF OURS, YET NO ONE SPOTTED HIM UNTIL HE WAS ALREADY PASSING OUR 2-3 O'CLOCK POS. THE COMBINATION OF EXTREMELY BRIGHT SUNLIGHT, THE OCEAN BELOW AND THE SCATTERED CLOUDS MAKE IT DIFFICULT TO SPOT ONCOMING TFC FROM A SAFE DISTANCE, ESPECIALLY IF YOU DON'T KNOW IT'S THERE! THE ONLY EFFECTIVE SOLUTION I CAN SEE IS FOR THE LCL FAA OFFICE IN SJU TO MANDATE CERTAIN ALTS FOR ACFT BELOW 3000' ON THE STT/STX CORRIDOR. SPECIFICALLY, 1000 OR 2000' FOR NBNDS TO STT, AND 1500 OR 2500' FOR SBNDS TO STX. 3000' CANNOT BE USED FOR NBNDS SINCE THIS IS AN IFR ALT OFTEN ASSIGNED BY ATC. ALL ACFT COULD BE REQUIRED TO SQUAWK MODE C AT ONE OF THESE ALTS, OR CLB TO A HIGHER VFR ALT ABOVE 3000' (3500, 4500, ETC). I HOPE THAT THE FAA CAN SEE THE LOGIC IN THIS BEFORE THERE IS AN ACCIDENT. THIS SIMPLE PROC WILL MERELY ORGANIZE THE ACFT THAT ALREADY USE THESE ALTS, INSTEAD OF EACH AIR CREW TRUSTING TO LUCK. IT WOULD BE EASY TO IMPLEMENT AND ENFORCE, SINCE I KNOW MANY OF OUR OWN PLTS ARE CONCERNED ABOUT IT.

Data retrieved from NASA's ASRS site as of July 2007 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.