From Halopedia, the Halo wiki
A rescue crawler is a type of rescue vehicle.
Meridian Station on Meridian maintained at least two rescue crawlers. On December 16, 2553, a number of personnel assisting with the construction of Pinnacle Station were trapped atop a mountain near an entrance to the Jenny Lynyn Tanatalte Mine. They had been aboard a transport shuttle when it had been commandeered by Jiralhanae from the Keepers of the One Freedom in pursuit of a rogue Office of Naval Intelligence unit. Rescue Crawlers were dispatched to pick the workers up. When the crawlers were around five kilometers from the mountain's base, Veta Lopis, present as part of a military operation, surmised that she and those with her would be gone before the crawlers arrived.
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