Date: 202006
Local time of day: 0601-1200
Location: ZZZ.TRACON, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Second reporter function: Pilot Flying; Captain
Anomaly: Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: On arrival into ZZZ; we were assigned the arrival and vectored directly to ZZZZZ; with instructions to cross at 12;000 ft. and 250 kts. from FL240. The altitude was set correctly; but the captain wanted to wait a little longer before descending. I was looking up information for the next leg in the ZZZ Procedures and didn't notice that the captain had waited too long to start a descent to meet the crossing restriction. By the time the captain caught the mistake we were unable to make the restriction without an excessive rate of descent. I contacted ATC to let them know we were too high; and they assigned us to cross ZZZ1 at 10;000 ft. and 250 kts. (As expected on the STAR). The second restriction was made.Everything was setup correctly; but I'd suggest that since we were in a VNAV-equipped aircraft for the past two days the captain got complacent in waiting for the TOD to let VNAV manage the descent; but we were in a 'classic' 700 and had to manually manage the descent.The Captain was using a steep descent; but within reason; with full speed brakes to try to make the crossing restriction; while not allowing the speed to climb up from the descent.


Second narrative: We were flying the arrival into ZZZ; however we were not given a descend via clearance. Instead we were given a clearance to fly direct to ZZZZZ and descend and maintain 12;000 ft. We had briefed the arrival and put 12;000 ft. in for the expected crossing at ZZZZZ1. When given the clearance direct to ZZZZZ and descend to 12;000 ft.; I as pilot flying selected DIR ZZZZZ in the FMS and put 12;000 ft. in R2. We confirmed it before executing then put 12;000 ft. in the altitude selector and confirmed it as well. I then continued the descent. I noticed that the snowflake and the 'banana bar' did not coincide with each other during the descent and realized that the FMS showed crossing ZZZ1 at 10;000 ft. but that ZZZZZ no longer showed 12;000 ft. in the FMS; the cause of the discrepancy. I increased our rate of descent but realized we would struggle to make the 12;000 ft. assigned crossing altitude at ZZZZZ. We immediately notified Center that we were going to be high and he then assigned us 10;000 ft. at ZZZ. We continued to descend and made the new crossing restriction at ZZZ with no problem. The flight continued without incident. I am not sure at what point the 12;000 ft. crossing restriction ceased to be in the FMS at ZZZZZ. I know I confirmed it with my pilot monitoring before executing the FMS. However when I noticed that the banana bar and the snowflake did not indicate what I wanted; it took me a moment to decide what the problem was. I mentioned the discrepancy to my pilot monitoring and we quickly figured out the cause of the issue. Unfortunately we were too close to ZZZZZ to descend to the assigned crossing altitude without a drastic rate of descent. That is when we asked ATC for relief on the crossing altitude and was given a new crossing altitude further down the line. I should have caught the issue earlier. I recognized that we were going to be high but was slow on the recovery. As a reserve pilot; before this trip I had not flown in over 3 weeks. I spent time in the manuals to remain comfortable; but I attribute this 'slowness' if you will on a lack of flying over the past 4 months. I do feel completely comfortable in the airplane; and upon realizing I was going to be high we immediately asked for some relief; which was the right course of action. However I should have noticed earlier that my VNAV reference and snowflake where not leading me where I wanted to go. For that I take responsibility. Having not been in the airplane much recently; it is a great reminder to remain vigilant throughout all aspects of the flight.


Synopsis: CRJ-700 flight crew requesting ATC revised clearance due to missing crossing altitude restriction.