Date: 202103
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: IMC
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ; Class E ZZZ
ATC / advisory: TRACON ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Troubleshooting; Time Pressure
Second reporter function: Pilot Flying; First Officer
Anomaly: Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem; Flight Crew Landed in Emergency Condition; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Once established in descent just below FL180; we received a call from the Flight Attendants that there was an odor in the vicinity of row X. This odor was described by FA 'A' as something similar to fuel and/or oil; but not a burning or acrid smell. The odor was not detectable to any other passengers or crew on the aircraft except the passengers in row X; to whom it was very noticeable; which was also confirmed by FA 'B'; but only when they walked up to row X. There was no visible plume anywhere in the airplane. The pilots did not detect any irregular odor in flight.The FO was flying the airplane (PF) so they took the radios as the CA (PM) looked in the QRH checklist. The comment about a fuel smell drove the pilots to suspect a fuel leak; but after running through the fuel leak checklist; no fuel leak indications (per checklist) were confirmed (fuel imbalance normal/not increasing; both engine fuel flow rates equivalent; quantity as expected for phase of flight plan). CA then confirmed with FA 'A' that the smell was indeed still noticeable; but there was still no plume and the odor was still confined to row X.We continued descent into ZZZ1 on what looked to be a fairly expedited vector; while we requested ARFF to be on standby at time of arrival. However; after we received another vector away from an expedited intercept course; we quickly [advised ATC] to gain traffic priority; which ATC quickly accommodated; clearing other aircraft from our path. We were cleared to land and we confirmed with Tower that ARFF would be standing by. Tower indicated we would exit [Runway] XXR at Taxiway 1 for ARFF coordination.Upon exit at Taxiway 1; we were cleared to cross runway XXL; and brought the aircraft to a stop on Taxiway 1 clear of runway. We requested ARFF check/scan the exterior of the aircraft for leaks/heat/fire/abnormalities. CA made a PA to pax noting that ARFF would be approaching the aircraft as a precaution. After ARFF indicated no abnormalities; we taxied to the gate; making clear to Ops that as an extra precaution; we would not start the APU. After we had taxied into the gate and set the parking brake; we immediately shut down (left-hand-side) engine #1; confirmed good/stable AC external power connection; then shut down (right-hand-side) engine #2. Prior to departure from ZZZ; we were sprayed with both Type I 'Deice' and Type IV 'Anti-Ice' fluid; with engines running; at the X Pad.After landing; FA 'B' said passengers had complained that the odor became more noticeable after landing gear was extended on final approach. FO also said that after landing they briefly noticed an odor.We could have [advised ATC] earlier on in the event. This would have allowed us traffic priority earlier in the descent (and speeds above 250 KIAS once below 10;000); getting us on the ground sooner and reducing the overall time of pax/FA exposure to fumes.We flew the same airplane the following day; and the airplane was cleared by Maintenance with no defects found. Nothing was wrong with the airplane itself. Fumes remaining localized in a certain area of the cabin suggests internal point source emission rather than external ingestion or airplane system malfunction. However; at time of writing; we still do not know; definitively; what caused the fumes.The FAs are commended for their prompt notification and accurate description of the nature and extent of the fumes. FO is commended for flying the aircraft while coordinating with ATC and requesting ARFF; while the CA ran checklists and coordinated with the FAs; then flying the approach almost to minimums. Working together seamlessly is key in these situations; and the CA commends the crew for a job well done.


Second narrative: Prior to departure from ZZZ; we were sprayed with both Type I and Type IV fluid; with engines running; at the South De-Ice Pad.Once established in descent just below FL180; we received a call from the FA's. I (the FO) assumed it was the FA's notification that they were seated. Instead; they communicated to the CA that there was an odor in the vicinity of row x. This odor was described by FA 'A' as something similar to fuel and/or oil; but not a burning smell. The odor was not detectable to any other passengers or crew on the aircraft except the passengers in row x; to whom it was very noticeable. The pilots did not detect any irregular odor in flight.I (the FO) was flying the airplane (PF) so I took the radios as the CA (PM) looked in the QRH checklist. Since the CA was communicating with the FA's; I trusted his lead on necessary checklists to run; as he had the first hand information on the situation in the cabin. During this time; we had entered IMC conditions; and I was flying the airplane and working the radios; receiving several heading; altitude and speed changes during this time.The comment about a fuel smell drove us to suspect a fuel leak; but after running through the fuel leak checklist; no fuel leak indications (per checklist) were confirmed (fuel imbalance normal/not increasing; both engine fuel flow rates equivalent; quantity as expected for phase of flight plan). CA then confirmed with FA 'A' that the smell was indeed still noticeable; but there was still no plume and the odor was still confined to row X.We continued descent into ZZZ1 on what looked to be a fairly expedited vector; during which I requested ARFF to be on standby at time of arrival. However; after we received another vector away from an expedited intercept course; we quickly [advised ATC] to gain traffic priority; which ATC quickly accommodated. We were cleared to land and we confirmed with Tower that ARFF would be standing by. Tower indicated we would exit XXR at Taxiway 1 for ARFF coordination.Upon landing; I cracked the Thrust Reversers (TRs); and briefly noticed a smell in the flight deck. I then decided that the use of TRs may not be the safest procedure; as it was still unclear what was causing this smell. Thus; I immediately stowed the TRs and decelerated using only the brakes (long runway; good braking action).Upon exit at Taxiway 1; we were cleared to cross runway XXL; and brought the aircraft to a stop on Taxiway 1 clear of XXL. We requested ARFF check/scan the exterior of the aircraft for leaks/heat/fire/abnormalities. CA made a PA to pax noting that ARFF would be approaching the aircraft as a precaution. After ARFF indicated no abnormalities; we taxied to the gate; making clear to Ops that as an extra precaution; we would not start the APU. After we had taxied into the gate and set the parking brake; we immediately shut down engine #1; confirmed good/stable AC external power connection; then shut down engine #2.After landing; FA 'B' said passengers had complained that the odor became more noticeable after landing gear was extended on final approach. This was my 2nd precautionary ARFF event on 2 consecutive workdays (though separated by a period of leave). Having had the time to reflect upon the first event; I felt calmer and more prepared this time. I focused on making a successful approach (almost down to minimums).One error I made was to start configuring and thus slowing down too early. Due to several heading changes and an ATC request for us to slow down while the aircraft in front of us on the approach sped up to best forward speed; I had felt momentarily disoriented regarding our distance to the ZZZ1. Luckily; my brain was about 5 miles ahead of the airplane. Once I realized my error; I paused further configuration (which was gear down flaps 3 at that time) until closer to the ZZZ1.Considerations that were made were items for fire and emergency evacuation; should a fire develop after landing. Luckily; this was not the case.To my knowledge; it is still unclear what caused the smell. If it would have been more severe (filling the entire cabin and flight deck); then the checklist for smoke/fumes would have been appropriate.Overall; I feel that this event was handled well by everyone involved.


Synopsis: EMB-175 flight crew reported a cabin fumes event during approach descent.