Narrative:

Everything was normal through takeoff. The first officer (first officer) did a to-takeoff. Prior to completing the after takeoff checklist; we got a ram air vlv fail caution message on the EICAS. Associated with this message was the pack 1-2 vlv fail status and the pack 1-2 vlv clsd status message. I selected climb mode and reset the packs; but that didn't help. The aircraft wasn't pressurizing; so I instructed the first officer to level off and I contacted ATC and told them that we needed to level off and run a few checklists before concluding whether we needed to declare an emergency. They gave us 3;000 feet and a heading and we complied. They asked if we were declaring an emergency and I responded 'standby.'we ran the ram air vlv fail checklist and requested to divert to [a nearby alternate] for longer runways and possible overweight landing. They continued to give us vectors while we ran checklists and communicated with the flight attendant; passengers; dispatch; and each other. We decided that since we were stable at a low altitude; the best course of action would be to continue burning fuel until we were under our max landing weight before attempting a landing. We slowed; dropped our gear and 9 degrees of flaps to help burn the extra fuel. Dispatch added [the nearby airport] as an alternate to our flight plan. The flight attendant was told that we would do a normal landing with no evacuation. While we were getting set up to land; dispatch asked if we would be ok to land in [departure airport] and we responded in the affirmative. I sent a message over ACARS to inform maintenance of the issue. We decided that I would do the landing; re-coupled the aircraft to my side and I took the controls.we informed the flight attendant; passengers and ATC that we wanted to go back to [departure airport] and while we were getting set up; we received an RA (resolution advisory) to climb. I disconnected the autopilot and followed the RA instructions until clear of conflict; then returned to altitude. We informed ATC and they continued to give us vectors with no further traffic issues. It looked like VFR traffic. The first officer set up for the approach. It was going to be a normal landing at this point; but tower rolled the crash fire rescue equipment (crash fire rescue) trucks as a precaution. We executed a normal landing. The passengers deplaned normally with no complaints. I made an appropriate entry in the aml (aircraft maintenance logbook) and contacted [maintenance control] per our SOP. Maintenance came and took the plane from us as we were taken to a new plane to continue the flight.a failure of the ram air valve caused the packs to fail to pressurize the airplane. This required us to return to the airport. The RA was caused by VFR traffic over the bay getting too close to our aircraft. I thought that everyone did a fantastic job in a crowded airspace to get us safely back on the ground.

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Original NASA ASRS Text

Title: EMB-140 flight crew reported returning to departure airport after noting a RAM AIR VLV FAIL EICAS message that resulted in their inability to pressurize the cabin.

Narrative: Everything was normal through takeoff. The FO (First Officer) did a TO-takeoff. Prior to completing the after takeoff checklist; we got a RAM AIR VLV FAIL caution message on the EICAS. Associated with this message was the PACK 1-2 VLV FAIL status and the PACK 1-2 VLV CLSD status message. I selected climb mode and reset the packs; but that didn't help. The aircraft wasn't pressurizing; so I instructed the FO to level off and I contacted ATC and told them that we needed to level off and run a few checklists before concluding whether we needed to declare an emergency. They gave us 3;000 feet and a heading and we complied. They asked if we were declaring an emergency and I responded 'standby.'We ran the RAM AIR VLV FAIL checklist and requested to divert to [a nearby alternate] for longer runways and possible overweight landing. They continued to give us vectors while we ran checklists and communicated with the Flight Attendant; passengers; Dispatch; and each other. We decided that since we were stable at a low altitude; the best course of action would be to continue burning fuel until we were under our max landing weight before attempting a landing. We slowed; dropped our gear and 9 degrees of flaps to help burn the extra fuel. Dispatch added [the nearby airport] as an alternate to our flight plan. The Flight Attendant was told that we would do a normal landing with no evacuation. While we were getting set up to land; Dispatch asked if we would be ok to land in [departure airport] and we responded in the affirmative. I sent a message over ACARS to inform Maintenance of the issue. We decided that I would do the landing; re-coupled the aircraft to my side and I took the controls.We informed the Flight Attendant; passengers and ATC that we wanted to go back to [departure airport] and while we were getting set up; we received an RA (Resolution Advisory) to climb. I disconnected the autopilot and followed the RA instructions until clear of conflict; then returned to altitude. We informed ATC and they continued to give us vectors with no further traffic issues. It looked like VFR traffic. The FO set up for the approach. It was going to be a normal landing at this point; but Tower rolled the CFR (Crash Fire Rescue) trucks as a precaution. We executed a normal landing. The passengers deplaned normally with no complaints. I made an appropriate entry in the AML (Aircraft Maintenance Logbook) and contacted [Maintenance Control] per our SOP. Maintenance came and took the plane from us as we were taken to a new plane to continue the flight.A failure of the RAM Air Valve caused the packs to fail to pressurize the airplane. This required us to return to the airport. The RA was caused by VFR traffic over the bay getting too close to our aircraft. I thought that everyone did a fantastic job in a crowded airspace to get us safely back on the ground.

Data retrieved from NASA's ASRS site 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.