Thud Ridge

{{Infobox mountain pass

| name = Thud Ridge

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| photo = 300px

| photo_caption = Location of Thud Ridge

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| elevation = {{convert|5000|ft}}

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| location = Vietnam

| topo =

| range = Tam Dao range

| coordinates = {{coord|21|30|22.2|N|105|36|31.02|E|type:pass|format=dms|display=inline,title}}

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Thud Ridge was the nickname given by United States Air Force F-105 Thunderchief pilots (the aircraft being nicknamed "Thud") during the Vietnam War to the Tam Dao range a 24 km, {{convert|5000|ft}} high ridge that ran parallel to the Red River approximately 32 km northwest of Hanoi, which was both a waypoint during air attacks and a terrain masking feature for ingressing fighters in the vicinity of Hanoi, North Vietnam.{{cite book|last=Broughton|first=Jack|title=Thud Ridge|publisher=J. B. Lippincott Company|year=1969|isbn=978-0-85979-116-8}}{{cite book|last=Kelley|first=Michael|title=Where we were in Vietnam|publisher=Hellgate Press|year=2002|isbn=978-1555716257|page=508}}

The North Vietnamese eventually installed anti-aircraft artillery on the ridge using heavy-lift helicopters.{{cite web|url=http://www.airspacemag.com/military-aviation/thuds-the-ridge-and-100-missions-north-47278311/?all&no-ist|title=Thuds, the Ridge, and 100 Missions North|publisher=Air & Space Magazine|date=February 2009|access-date=4 January 2015}}

Phúc Yên Air Base is located at the base of the ridge, while Kép Air Base is located east of the ridge.

The ridge features heavily in the book Thud Ridge.