There were six heavy radars between Hopedale and St. Johns located at Hopedale, Cartwright, St. Anthony, Stephenville, Gander and Red Cliff (St. Johns). To increase low altitude coverage along this line and provide some back-up for these radars, a small, light-weight radar (the AN/FPS-14), called a gap-filler, was to be placed between these heavy radars. The AN/FPS-14 was a medium-range search radar which was designed and built by Bendix as a gap-filler radar to provide low altitude coverage. It operated in the S-band at a frequency between 2700 and 2900 MHz and could detect traffic at a range of 65 miles. The system was deployed to locations within the Pinetree Line in Newfoundland and Labrador. There were six gap filler sites (approved in March 1955). Details are as follows:
| Site | Gap Filler Location | Latitude | Longitude | Detachment | # Photos | |
| N-22B | Elliston Ridge, NF | 48 36 48 N | 55 02 12 W | Detachment 1, 642nd Sq. Red Cliff (St. Johns), NF |
143 | |
| N-27C | Fox Harbour, Labrador | 52 51 50 N | 55 40 00 W | Detachment 3, 922st Sq. Cartwright, Labrador |
445 | |
| N-26B | La Scie, NF | 49 59 24 N | 55 33 24 W | Detachment 2, 921st Sq. St. Anthony, NF |
172 | |
| N-27A | Cut Throat Island, Labrador | 54 30 00 N | 57 07 25 W | Detachment 1, 922nd Sq. Cartwright, Labrador |
102 | |
| N-27B | Spotted Island, Labrador | 53 30 55 N | 55 45 20 W | Detachment 2, 922nd Sq. Cartwright, Labrador |
110 | |
| N-28A | Cape Makkovik, Labrador | 55 13 30 N | 59 08 45 W | Detachment 1, 923rd Sq. Hopedale, Labrador |
206 |
Unlike the RCAF gap-filler units, the USAF gap-filler units were all manned sites and the number of personnel employed at these locations varied depending on the responsibilities allocated to the gap-filler. Elliston Ridge, Fox Harbour and Cape Makkovik became operational in February 1957. Cut Throat Island, Spotted Island and La Scie were scheduled to be operational by the end of April, 1957.
This page is located at
http://www.pinetreeline.org/gap/gap2.html
Updated: April 23, 2002