✈ Spire Tail-Tracer

‹ Aircraft

RA-73653 / 151FB5

165 flights over 74 days · 2.23 legs/day · base ULLI · St. Petersburg · operators: AUL

165
Flights
22
Airports served
4%
ADS-B observed
19
Ferry / no-flightnum

Aircraft identity

B738 B738
— · reg RA-73653
· free OpenSky data

Rotation map · last 14 days of legs

Daily rotations

2026-06-23 3 legs AUL
ULLI → UMKK → ULMM → UMKK
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL513 · 5N513 · sched 10:55Z
EYND→ ULMM EYND · Nida → ULMM · Murmansk ⚠ gap intl AUL530 · 5N530 · sched 13:35Z
ULMM→ UMKK ULMM · Murmansk → UMKK · Kaliningrad AUL529 · 5N529 · sched 17:25Z
2026-06-22 5 legs AUL
UNNT → ULMM → ULLI → UMKK → ULLI → ?
UNNT→ ULMM UNNT · Novosibirsk → ULMM · Murmansk AUL572 · 5N507 · sched 06:45Z
ULMM→ ULLI ULMM · Murmansk → ULLI · St. Petersburg AUL508 · 5N508 · sched 09:15Z
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL513 · 5N513 · sched 11:55Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL514 · 5N514 · sched 14:35Z
?→ ? — → — ferry · sched Z
2026-06-21 2 legs AUL
ULLI → UWWW → UNNT
ULLI→ UWWW ULLI · St. Petersburg → UWWW · Samara AUL581 · 5N581 · sched 12:20Z
ULLI→ UNNT ULLI · St. Petersburg → UNNT · Novosibirsk ⚠ gap AUL571 · 5N571 · sched 19:45Z
2026-06-20 1 legs AUL
ULLI → ?
ULLI→ ? ULLI · St. Petersburg → — ferry AUL541 · sched Z
2026-06-19 2 legs AUL
ULLY → UMKK → ULLI
ULLY→ UMKK ULLY → UMKK · Kaliningrad AUL505 · 5N505 · sched 05:40Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 08:20Z
2026-06-16 1 legs AUL
ULSW → UWKD
ULSW→ UWKD ULSW · Putilovo → UWKD · Kazan AUL537 · 5N537 · sched 16:10Z
2026-06-15 3 legs AUL
ULLI → UMKK → ULLI → ?
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 05:40Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 08:20Z
?→ ? — → — AUL574 · 5N574 · sched Z
2026-06-14 3 legs AUL
ULLI → UMKK → ULLI → ?
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL513 · 5N513 · sched 11:10Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL514 · 5N514 · sched 13:50Z
?→ ? — → — AUL573 · 5N573 · sched Z
2026-06-13 2 legs AUL
ULSK → UMKK → UUEE
ULSK→ UMKK ULSK · Gatchina → UMKK · Kaliningrad AUL251 · 5N251 · sched 05:55Z
UMKK→ UUEE UMKK · Kaliningrad → UUEE · Moscow AUL252 · 5N252 · sched 09:15Z
2026-06-10 2 legs round-trip AUL
UUEE → UMKK → UUEE
UUEE→ UMKK UUEE · Moscow → UMKK · Kaliningrad AUL251 · 5N251 · sched 05:55Z
UMKK→ UUEE UMKK · Kaliningrad → UUEE · Moscow AUL252 · 5N252 · sched 09:15Z
2026-06-08 4 legs AUL
UNOO → ? → ? → UNOO → ?
UNOO→ ? UNOO · Omsk → — AUL862 · 5N862 · sched Z
?→ ? — → — ferry · sched Z
?→ UNOO — → UNOO · Omsk ferry AUL861 · sched Z
?→ ? — → — AUL164 · 5N164 · sched Z
2026-06-07 2 legs round-trip AUL
UMKK → ULLI → UMKK
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched Z
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched Z
2026-06-06 1 legs AUL
ULLI → ULMM
ULLI→ ULMM ULLI · St. Petersburg → ULMM · Murmansk AUL517 · 5N517 · sched 12:00Z
2026-06-05 1 legs AUL
? → ?
?→ ? — → — AUL545 · 5N545 · sched Z
2026-06-04 3 legs AUL
UUEE → ? → ? → ?
UUEE→ ? UUEE · Moscow → — ferry · ⏱ 09:35– (Nonem)
?→ ? — → — ferry · sched Z
USSS→ ? USSS · Yekaterinburg → — AUL293 · 5N293 · sched Z
2026-06-03 2 legs round-trip AUL
UUEE → UMKK → UUEE
UUEE→ UMKK UUEE · Moscow → UMKK · Kaliningrad AUL251 · 5N251 · sched 05:55Z
UMKK→ UUEE UMKK · Kaliningrad → UUEE · Moscow AUL252 · 5N252 · sched 09:15Z
2026-06-02 1 legs
USSS → ?
USSS→ ? USSS · Yekaterinburg → — ferry · sched Z
2026-06-01 1 legs
? → ULLI
?→ ULLI — → ULLI · St. Petersburg ferry · sched Z
2026-05-30 1 legs AUL
ULSW → ULMM
ULSW→ ULMM ULSW · Putilovo → ULMM · Murmansk AUL517 · 5N517 · sched 12:00Z
2026-05-29 1 legs AUL
? → ?
?→ ? — → — AUL808 · 5N808 · sched Z
2026-05-26 1 legs AUL
UUEE → ULMM
UUEE→ ULMM UUEE · Moscow → ULMM · Murmansk AUL521 · 5N521 · sched 09:20Z
2026-05-25 2 legs round-trip AUL
UUEE → UMKK → UUEE
UUEE→ UMKK UUEE · Moscow → UMKK · Kaliningrad AUL251 · 5N251 · sched 14:15Z
UMKK→ UUEE UMKK · Kaliningrad → UUEE · Moscow AUL252 · 5N252 · sched 17:30Z
2026-05-24 1 legs AUL
ULLI → ULAA
ULLI→ ULAA ULLI · St. Petersburg → ULAA · Archangelsk AUL152 · 5N152 · sched 11:45Z
2026-05-23 1 legs AUL
UNOO → ?
UNOO→ ? UNOO · Omsk → — AUL862 · 5N862 · sched Z
2026-05-22 4 legs AUL
USSS → ULLI → USSS → UNOO → ?
USSS→ ULLI USSS · Yekaterinburg → ULLI · St. Petersburg AUL502 · 5N502 · sched 02:15Z
USSS→ USSS USSS · Yekaterinburg → USSS · Yekaterinburg ferry ⚠ gap · sched Z
?→ UNOO — → UNOO · Omsk AUL861 · 5N861 · sched Z
UWWG→ ? UWWG · Samara → — ⚠ gap AUL547 · 5N547 · sched Z
2026-05-21 2 legs round-trip AUL
ULLI → ULMM → ULLI
ULLI→ ULMM ULLI · St. Petersburg → ULMM · Murmansk AUL507 · 5N507 · sched 07:00Z
ULMM→ ULLI ULMM · Murmansk → ULLI · St. Petersburg AUL508 · 5N508 · sched 09:30Z
2026-05-20 1 legs
USSS → ?
USSS→ ? USSS · Yekaterinburg → — ferry · sched Z
2026-05-18 2 legs round-trip AUL
ULLI → UMKK → ULLI
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 05:40Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 08:20Z
2026-05-17 2 legs round-trip AUL
UUYY → ULLI → UUYY
UUYY→ ULLI UUYY · Syktyvkar → ULLI · St. Petersburg AUL504 · 5N504 · sched 19:50Z
?→ UUYY — → UUYY · Syktyvkar ferry · sched Z
2026-05-16 3 legs AUL
? → ? → ULAA → ?
?→ ? — → — ferry · sched Z
UMKK→ ULAA UMKK · Kaliningrad → ULAA · Archangelsk AUL176 · 5N176 · sched Z
?→ ? — → — AUL175 · 5N175 · sched Z
2026-05-15 3 legs AUL
UWUU → ULLI → ? → ?
UWUU→ ULLI UWUU · Ufa → ULLI · St. Petersburg AUL592 · 5N592 · ⏱ 02:16– (Nonem)
UWUM→ ? UWUM → — ferry ⚠ gap · sched Z
UWWE→ ? UWWE · Tolyatti → — ferry · sched Z
2026-05-14 2 legs AUL
ULLI → UMKK → ULLY
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 06:05Z
UMKK→ ULLY UMKK · Kaliningrad → ULLY AUL506 · 5N506 · sched Z
2026-05-13 1 legs AUL
UWUU → ULLI
UWUU→ ULLI UWUU · Ufa → ULLI · St. Petersburg AUL592 · 5N592 · sched 02:10Z
2026-05-09 4 legs AUL
ULLI → UMKK → ULLI → UMKK → ULMM
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 06:40Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 09:20Z
ULMM→ UMKK ULMM · Murmansk → UMKK · Kaliningrad ⚠ gap AUL529 · 5N529 · sched 19:55Z
EYND→ ULMM EYND · Nida → ULMM · Murmansk ⚠ gap intl AUL530 · 5N530 · sched 23:40Z
2026-05-08 3 legs AUL
ULMM → ULLI → UNNT → ?
ULMM→ ULLI ULMM · Murmansk → ULLI · St. Petersburg AUL508 · 5N508 · sched 09:30Z
ULLI→ UNNT ULLI · St. Petersburg → UNNT · Novosibirsk AUL571 · 5N571 · sched 19:45Z
UNNT→ ? UNNT · Novosibirsk → — AUL572 · 5N572 · sched Z
2026-05-07 1 legs AUL
? → UNNT
?→ UNNT — → UNNT · Novosibirsk AUL571 · 5N571 · sched Z
2026-05-06 2 legs AUL
ULLI → UMKK → ULLY
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 06:05Z
UMKK→ ULLY UMKK · Kaliningrad → ULLY AUL506 · 5N506 · sched 08:45Z
2026-05-04 1 legs AUL
UWOO → ULLI
UWOO→ ULLI UWOO · Orenburg → ULLI · St. Petersburg AUL588 · 5N588 · sched 02:30Z
2026-05-03 4 legs AUL
UMKK → ULLY → UMKK → ULLI → ?
UMKK→ ULLY UMKK · Kaliningrad → ULLY AUL534 · 5N534 · sched 04:35Z
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad ⚠ gap AUL513 · 5N513 · sched 11:10Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL514 · 5N514 · sched 14:40Z
?→ ? — → — AUL3104 · 5N3104 · sched Z
2026-05-02 4 legs AUL
ULLI → UMKK → ULLI → UMKK → ?
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 06:40Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 09:20Z
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL533 · 5N533 · sched 16:20Z
UMKK→ ? UMKK · Kaliningrad → — AUL3103 · 5N3103 · sched Z
2026-05-01 3 legs AUL
ULLY → ? → ? → ?
ULLY→ ? ULLY → — AUL533 · 5N533 · sched Z
?→ ? — → — AUL574 · 5N574 · sched Z
UMKK→ ? UMKK · Kaliningrad → — AUL534 · 5N534 · sched Z
2026-04-30 1 legs AUL
? → ?
?→ ? — → — AUL573 · 5N573 · sched Z
2026-04-28 2 legs round-trip AUL
UMKK → ULLI → UMKK
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched Z
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched Z
2026-04-27 2 legs AUL
UNNT → ULLI → ULMM
UNNT→ ULLI UNNT · Novosibirsk → ULLI · St. Petersburg AUL572 · 5N572 · sched 01:05Z
ULLI→ ULMM ULLI · St. Petersburg → ULMM · Murmansk AUL507 · 5N507 · sched 06:45Z
2026-04-26 1 legs AUL
ULLI → UNNT
ULLI→ UNNT ULLI · St. Petersburg → UNNT · Novosibirsk AUL571 · 5N571 · sched 19:45Z
2026-04-25 2 legs AUL
UNNT → EYND → ULLI
UNNT→ EYND UNNT · Novosibirsk → EYND · Nida intl AUL572 · 5N505 · sched 06:40Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg ⚠ gap AUL506 · 5N506 · sched 09:20Z
2026-04-24 3 legs AUL
UWUU → ULLI → UWWW → UNNT
UWUU→ ULLI UWUU · Ufa → ULLI · St. Petersburg AUL592 · 5N592 · sched 02:10Z
ULLI→ UWWW ULLI · St. Petersburg → UWWW · Samara AUL582 · 5N531 · sched 06:20Z
ULLI→ UNNT ULLI · St. Petersburg → UNNT · Novosibirsk ⚠ gap AUL571 · 5N571 · sched 19:45Z
2026-04-23 2 legs round-trip AUL
ULLI → UMKK → ULLI
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 06:05Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 08:45Z
2026-04-22 2 legs round-trip AUL
UUYY → ULLI → UUYY
UUYY→ ULLI UUYY · Syktyvkar → ULLI · St. Petersburg AUL504 · 5N504 · sched 20:00Z
?→ UUYY — → UUYY · Syktyvkar ferry · sched Z
2026-04-21 3 legs AUL
UNNT → ULLI → ULLI → ?
UNNT→ ULLI UNNT · Novosibirsk → ULLI · St. Petersburg AUL572 · 5N572 · sched 01:05Z
UWWG→ ULLI UWWG · Samara → ULLI · St. Petersburg ⚠ gap AUL532 · 5N532 · sched 09:15Z
UUYY→ ? UUYY · Syktyvkar → — ⚠ gap AUL504 · 5N504 · ⏱ 19:47– (Nonem)
2026-04-20 4 legs AUL
UNNT → ULLI → ULMM → ULLI → UWWW
UNNT→ ULLI UNNT · Novosibirsk → ULLI · St. Petersburg AUL572 · 5N572 · sched 01:05Z
ULLI→ ULMM ULLI · St. Petersburg → ULMM · Murmansk AUL507 · 5N507 · sched 06:45Z
ULMM→ ULLI ULMM · Murmansk → ULLI · St. Petersburg AUL508 · 5N508 · sched 09:15Z
ULLI→ UWWW ULLI · St. Petersburg → UWWW · Samara AUL532 · 5N581 · sched 12:20Z
2026-04-19 1 legs AUL
USSS → ?
USSS→ ? USSS · Yekaterinburg → — AUL294 · 5N294 · sched Z
2026-04-18 2 legs AUL
ULLI → UMKK → UUEE
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 06:40Z
UMKK→ UUEE UMKK · Kaliningrad → UUEE · Moscow AUL252 · 5N252 · sched 09:15Z
2026-04-17 2 legs round-trip AUL
ULLI → ULMM → ULLI
ULLI→ ULMM ULLI · St. Petersburg → ULMM · Murmansk AUL507 · 5N507 · sched 07:00Z
?→ ULLI — → ULLI · St. Petersburg ferry · sched Z
2026-04-15 2 legs AUL
UWUU → ULLI → UNNT
UWUU→ ULLI UWUU · Ufa → ULLI · St. Petersburg AUL592 · 5N592 · sched 02:10Z
ULLI→ UNNT ULLI · St. Petersburg → UNNT · Novosibirsk AUL571 · 5N571 · sched 19:45Z
2026-04-13 3 legs AUL
UUYY → ULLI → ? → ULLI
UUYY→ ULLI UUYY · Syktyvkar → ULLI · St. Petersburg AUL504 · 5N504 · sched 19:50Z
?→ ? — → — AUL505 · 5N505 · sched Z
?→ ULLI — → ULLI · St. Petersburg AUL506 · 5N506 · sched Z
2026-04-12 2 legs AUL
ULLI → UWWW → ?
ULLI→ UWWW ULLI · St. Petersburg → UWWW · Samara AUL581 · 5N581 · sched 12:20Z
?→ ? — → — ferry · sched Z
2026-04-11 4 legs AUL
UNNT → UMKK → URML → ? → ?
UNNT→ UMKK UNNT · Novosibirsk → UMKK · Kaliningrad AUL238 · 5N251 · sched 05:55Z
UUEE→ URML UUEE · Moscow → URML · Makhachkala ⚠ gap AUL207 · 5N207 · sched 14:00Z
?→ ? — → — AUL252 · 5N252 · sched Z
?→ ? — → — AUL293 · 5N293 · sched Z
2026-04-10 2 legs AUL
UUEE → UUEE → ?
UUEE→ UUEE UUEE · Moscow → UUEE · Moscow AUL521 · 5N521 · sched 07:30Z
?→ ? — → — AUL238 · 5N238 · sched Z
2026-04-09 2 legs round-trip AUL
UUEE → USSS → UUEE
UUEE→ USSS UUEE · Moscow → USSS · Yekaterinburg AUL293 · 5N293 · sched 23:25Z
USSS→ UUEE USSS · Yekaterinburg → UUEE · Moscow AUL294 · 5N294 · sched 02:45Z
2026-04-08 4 legs AUL
UNNT → UUEE → UMKK → UUEE → ?
UNNT→ UUEE UNNT · Novosibirsk → UUEE · Moscow AUL238 · 5N238 · sched 00:45Z
UUEE→ UMKK UUEE · Moscow → UMKK · Kaliningrad AUL251 · 5N251 · sched 05:55Z
UMKK→ UUEE UMKK · Kaliningrad → UUEE · Moscow AUL252 · 5N252 · sched 09:15Z
?→ ? — → — AUL207 · 5N207 · sched Z
2026-04-07 2 legs AUL
UUEE → ULMM → UNNT
UUEE→ ULMM UUEE · Moscow → ULMM · Murmansk AUL521 · 5N521 · sched 07:25Z
UUEE→ UNNT UUEE · Moscow → UNNT · Novosibirsk ⚠ gap AUL227 · 5N237 · sched 19:50Z
2026-04-06 3 legs AUL
ULAA → UUEE → UMKK → UUEE
ULAA→ UUEE ULAA · Archangelsk → UUEE · Moscow AUL218 · 5N218 · ⏱ 11:42–14:33 (171m)
UUEE→ UMKK UUEE · Moscow → UMKK · Kaliningrad AUL251 · 5N251 · sched 14:15Z
UMKK→ UUEE UMKK · Kaliningrad → UUEE · Moscow AUL252 · 5N252 · sched 17:30Z
2026-04-05 4 legs AUL
ULLI → UWUU → ULAA → UWKD → ?
ULLI→ UWUU ULLI · St. Petersburg → UWUU · Ufa AUL591 · 5N591 · sched 22:45Z
ULLI→ ULAA ULLI · St. Petersburg → ULAA · Archangelsk ⚠ gap AUL218 · 5N218 · sched 14:30Z
UUEE→ UWKD UUEE · Moscow → UWKD · Kazan ⚠ gap AUL227 · 5N227 · sched 17:15Z
UWUU→ ? UWUU · Ufa → — ⚠ gap AUL592 · 5N592 · sched Z
2026-04-04 1 legs
? → ?
?→ ? — → — ferry · sched Z
2026-04-03 2 legs AUL
ULLP → USCC → ?
ULLP→ USCC ULLP · St. Petersburg → USCC · Chelyabinsk AUL527 · 5N527 · sched 23:30Z
?→ ? — → — ferry · sched Z
2026-04-02 2 legs round-trip AUL
ULLI → UMKK → ULLI
ULLI→ UMKK ULLI · St. Petersburg → UMKK · Kaliningrad AUL505 · 5N505 · sched 06:05Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 08:45Z
2026-04-01 2 legs round-trip AUL
ULLI → USCC → ULLI
ULLI→ USCC ULLI · St. Petersburg → USCC · Chelyabinsk AUL527 · 5N527 · sched 22:10Z
USCC→ ULLI USCC · Chelyabinsk → ULLI · St. Petersburg AUL528 · 5N528 · sched 02:00Z
2026-03-31 2 legs AUL
? → ? → ?
?→ ? — → — AUL507 · 5N507 · sched Z
?→ ? — → — AUL508 · 5N508 · sched Z
2026-03-30 3 legs AUL
ULLI → USSS → ULLI → UWWW
ULLI→ USSS ULLI · St. Petersburg → USSS · Yekaterinburg AUL501 · 5N501 · sched 22:35Z
USSS→ ULLI USSS · Yekaterinburg → ULLI · St. Petersburg AUL502 · 5N502 · sched 02:15Z
ULLI→ UWWW ULLI · St. Petersburg → UWWW · Samara AUL531 · 5N531 · sched 06:20Z
2026-03-29 2 legs AUL
ULMM → ULLI → UUEE
ULMM→ ULLI ULMM · Murmansk → ULLI · St. Petersburg AUL508 · 5N508 · sched 09:30Z
ULAA→ UUEE ULAA · Archangelsk → UUEE · Moscow ⚠ gap AUL218 · 5N218 · ⏱ 16:00–18:56 (177m)
2026-03-28 1 legs AUL
UNNT → UUEE
UNNT→ UUEE UNNT · Novosibirsk → UUEE · Moscow AUL238 · 5N238 · sched 02:15Z
2026-03-27 3 legs AUL
ULAA → USSS → UNNT → ULLI
ULAA→ USSS ULAA · Archangelsk → USSS · Yekaterinburg AUL501 · 5N501 · ⏱ 10:55– (Nonem)
UUEE→ UNNT UUEE · Moscow → UNNT · Novosibirsk ⚠ gap AUL237 · 5N237 · sched 21:15Z
USSS→ ULLI USSS · Yekaterinburg → ULLI · St. Petersburg ⚠ gap AUL502 · 5N502 · sched Z
2026-03-26 4 legs AUL
ULSG → UMKK → ULLI → UWWW → ULLI
ULSG→ UMKK ULSG · Gostilitsy → UMKK · Kaliningrad AUL505 · 5N505 · sched 05:50Z
UMKK→ ULLI UMKK · Kaliningrad → ULLI · St. Petersburg AUL506 · 5N506 · sched 08:30Z
ULLI→ UWWW ULLI · St. Petersburg → UWWW · Samara AUL581 · 5N581 · sched 12:35Z
UWWW→ ULLI UWWW · Samara → ULLI · St. Petersburg AUL582 · 5N582 · sched 15:35Z